The success of meditation depends on the exhaustion of our samskaras (reactive momenta). Yet some physical, mental and spiritual preparation can help us in this process. Following guidelines are primarily extracted from instructions given by senior yogiis for spiritual aspirants (yoga practitioners).
Physical Preparation:
1. Be firm on 16 Points (including all parts of Carya'carya)
2. Keep the body cool and calm
3. Keep away from dust, smoke and pollution
4. Maintain clean clothes and environment, especially the place of sa'dhana'
5. Use water after urination without fail (be sure to carry a shaoca mainjusa)
6. Use soap, oil, and comb daily
7. Brush the teeth and scrape the tongue each morning before sa'dhana' and food
8. Do Na'sa'pa'na at the time of bath or half bath (but only if the stomach is empty)
9. Use a lufa sponge regularly to remove dead skin cells
10. Don't use artificially perfumed things
11. Don't share personal items of hygiene
12. Eat only good sa'ttvika food
13. Not more than 4 meals per day and 4 items per meal
14. Eat and prepare food with proper ideation
15. Only accept food offered with good intention and noble motive
16. Eat only when hungry: "If in doubt about eating, don't eat; if in doubt about going to the
toilet, go to the toilet"
17. Eat slowly and don't overeat
18. Eat when the right nostril (Piungala na'd'ii) is active
19. Food should be substantial, nutritious, and alkaline. Raw food is best
20. Avoid refined sugar, hot spices, heavy oil and chemicals
21. Eat lightly at night (e.g. milk and fruits), and take only liquids after 20.00 hours
22. Drink pure water in sufficient quantity  (with lemon and a little salt), but not too much at a time
23. Keep the stomach clean and healthy (Ud'd'ayana' Mudra')
24. Avoid constipation at all costs (Utks'epa Mudra'): "One who has control of the bowels grows stronger;
one who has control over his semen enjoys a long life".
25. Observe fasting on Pu'rn'ima' and Ama'vasya' in addition to Eka'dashi
26. Do a'sanas twice a day, according to the rules, including Kaoshikii and for brothers,do Tan'd'ava  (instead of counting, repeat Is't'a Mantra as a unit of time) as well.
27. A'sanas should be done after sa'dhana' (or wait some time before starting sa'dhana').
28. Sleep when tired, on a firm bed, lying initially on the left side for digestion.
29. Before sleeping, do sa'dhana', then repeat your IM as you fall asleep.
30. Rise in the Brahmamuhu'rtta (don't oversleep)
31. Sleep on your own bed and don't allow anyone else to sleep on it
32. Don't sleep on your sa'dhana' mat/ blanket
33. Don't do sa'dhana' on your bed (except for Gurusakasha)
34. Exercise regularly, including walking in fresh air after dinner
35. Breath diaphragmatically, through the nose
36. If ill, first take appropriate treatment from Yaogika Cikitsa' and Microvita Meds, then other natural therapies, then allopathic medicine, if necessary.
37. Avoid ta'masika places such as bars, restaurants, clubs, etc.
38. Rather than absorb the vibration from the surroundings, be like sandalwood and fill the air with your own vibration.
40. Make a daily routine according to your personal schedule and circumstance.
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Psychic Preparation:

1. Follow all conduct rules including 16 Points, 15 Shiilas, 1 Point Local and the social code as per Carya'carya parts 1, 2, and 3.
2. Be established in Yama and Niyama
3. Keep receptive to all spiritually stimulating tanma'tras (like a bee collecting honey)
4. Take second lesson with ideation at every step ( lose yourself in Brahmabha'va)
5. Half Iishvara Pran'idha'na helps 1 and 5 ( IM with ideation and devotion).
6. Half dhya'na (think He is constantly with you).
7. Maintain purity of mind.
8. Shravan'a, ma'nana and nidhidhya'sana are essential preparation for dhya'na (nidhidhya'sana means to prepare the mind for spiritual ideation after withdrawing it from other occupations).
9. Always think He is seeing you
10. Always think you are serving Him
11. Sa'dhana' is to please the Supreme, so do all that pleases the Supreme Consciousness.
12. Implicit faith and sincerity
13. Acceptance and constant vigilance
14. Intense urge and determination
15. Simplicity and balance of mind
16. Maintain constant awareness of the goal, and persistent endeavour to attain the goal
17. Avoid all crude sensory input and expression, especially for half an hour after sa'dhana'
18. Sa'dhu behaviour (politeness, courtesy and noble conduct)
19. Don't live in the past: "Vartta'manesu Vartteta"
20. Don't compare yourself to others
21. Keep proper sa'tsaunga (sa'tsaunga is of 3 types: Guru dhya'na, sva'dhya'ya, company of
elevated sa'dhakas)
22. Do sva'dhya'ya daily with proper understanding (SS, AV, Shiva, Krs'n'a)
23. Play recordings of PS and kiirtan throughout the day
24. Observe manovrata for at least half an hour each day e.g. while resting after lunch
25. Before any important work, do Guru Pu'ja', surrendering the results to Him
26. Serve the needy according to your capacity e.g. Sada'vrata
27. Don't accept service from others as far as possible
28. Don't be afraid of suffering: "Accept all sufferings as rewards". They are His blessings and will lead to purity.
29. Become a good Proutist (sa'dhana' and Prout are complementary)
30. Consider all with Neohumanistic outlook and feeling of Cosmic brotherhood
31. Record all spiritually inspiring experiences for future inspiration
32. Do self analysis at the end of each day, and plan for the next day (review your life in relation to what Ba'ba' would have done; have my thoughts, words and actions pleased Him?)
33. For any strong and recurring vrtti, cultivate the opposite tendency. "Overcome censure by praise; darkness by light"
34. Study review on occasion (AS, I and I, PNS, etc.)
35. Take time to reflect on your universality
36. Be patient and persevering. Don't be concerned about apparent setbacks. "Man proposes and God disposes." Movement is always systaltic and He is testing our resolve
37. Get any doubts or questions clarified immediately by a respectable A'ca'rya with the requisite knowledge
38. Cultivate devotion at each moment. Ask only for Para'bhakti
39. For devotion, there are two important points: think "He is mine and mine alone", and think you are giving unilateral service to Him ("I am serving Him to give Him bliss")
40. Look only to Him. Don't look left or right. Look straight to Ba'ba'. Hold onto His feet through all adversity
41. Surrender to Him. Attain Him. "Guru Krpahi Kevalam"
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Sa'dhana':

1. Do sa'dhana' at the proper time and place ("Same time, place, a'sana")
2. There should be no delay between morning duties and sa'dhana'
3. Do Prabha't Sam'giita to evoke devotional feeling
4. Do kiirtan loudly until fully vibrated (also as much as possible throughout the day; kiirtan attracts
positive microvita)
5. Do sa's't'a'unga pran'a'm at His lotus feet before and after sa'dhana'. "I surrender myself to You. Let Your will be done" (if not practical to do it physically, then at least mentally)
6. Do Shashaunga'sana to stimulate the pineal gland
7. Use a dark coloured insulating mat (e.g. woolen) as a'sana, and don't use it for anything else
8. Sit in the correct dhya'na'sana for each lesson, keeping the spine straight and the body still
9. Take firm determination to have good sa'dhana'. Be serious about it. "I will sit until I realize myself"
10. Create such a circumstance that you will have psychic space and freedom during sa'dhana'
11. Pratikriti and pratik should be displayed in an elevated position before you
12. Breath should be flowing through the left nostril (id'a' na'd'ii active). Both 3 and 5 bring on Id'a'. But best is Sus'umna' na'd'ii (both nostrils active). Sus'umna' is strengthened by 3
13. Breath should be slow and relaxed, with emphasis on Shu'n'ya kumbhaka
14. Do japa of Is't'a Mantra 80 times before starting lessons
15. Don't rush shu'ddhis
16. Do all lessons each time, allowing enough time for each one (4 is necessary for 6, 5 helps 1, 3 helps 1, 5 and 6)
17. Do lessons properly, with correct ideation and full concentration at appropriate cakras
18. For IM; correct pronunciation, ideation and devotional feeling are all essential
19. Never repeat IM aloud
20. For dhya'na, think: "I am the object and He is the subject. He is seeing me." (1 and 6 are both dhya'na)
21. If failure to concentrate, do more kiirtan and Guru Pu'ja' (especially during 6)
22. Do Guru Pu'ja' after sa'dhana' in front of Pratikriti, or if Pratikriti is not available, mentally envision Ba'ba' with eyes closed. (It is also good to do Guru Pu'ja' before sa'dhana')
23. Do Varn'a'rghya'rdana after GP: "All that I have, including my mind, I place at Your altar. Please
oblige and accept it."
24. If any physical or psychic problem is disturbing your sa'dhana', do GP and VG as many times as necessary, surrendering the object each time
25. After sa'dhana', remain alone for some time in contemplation
26. Don't touch food, people or animals for at least half an hour
after sa'dhana' (If unavoidable, take strong second lesson first)
27. Get all lessons as soon as possible
28. One can do 3 and 5 any time, even after food
29. Do only 1 collectively
30. Do Gurusakasha immediately on waking, followed by Gurupran'a'm
31. Whenever you feel drained, do sa'dhana' until fully recharged
32. Observe sa'dhana' day regularly to recharge and inspire. (Make sure you have the necessary physical and psychic freedom, and only eat as much as you need to keep your mind off your stomach)
33. Always do sa'dhana' as if it were for the last time
34. Keep in mind the goal of sa'dhana': You are not trying to gain anything; rather you are trying to lose yourself.
"Where I is He is not. Where He is I is not."