raihan,
This is such a complicated issue and there is no one size fits all approach. My advice (as I started with nootropics for the same reasons as you to study more effectively) is to try a comprehensive formula from a reputable company and try not to tweak things too much as you can really screw yourself up if you don't have experience. Furthermore the younger you are the less in the way of nootropics you need.
try AOR Ortho-Mind as it seems to be a fairly complete formula and AOR is reputable
You say there is no "one size fits all", yet you recommend AOR ortho-mind. I think it is much better and funner to tweak one's own nootropic regimen.
Anyways, miraz, like I've stated in other threads, you want to start out with a basic piracetam and choline source (cdp-choline, alpha-gpc, lecithin, choline citrate, choline bitartrate, DMAE, centrophenoxine). Take piracetam and choose one of the choline sources I have listed in parentheses. The cheap route would be to buy piracetam in a bulk powder format from bulknutrition.com or BAC (beyond-a-century.com). If you are tight on money, also buy choline citrate or bitartrate. If you want to "step it up a notch" (as Emerald Lagasse would say), you can add ALCAR a.k.a. acetyl-l-carnitine and ALA a.k.a. alpha lipoic acid. You can find both of these at bulknutrition.com, but I'm not sure about BAC.
Start low and work your way up. An example starter stack would be like this.
--Piracetam - 800mg 3 times a day (You will have to experiment to see which dose works best for you. Some ppl take up around 2.4 grams 3 times a day or so if not more)
--Choline bitartrate or citrate - 1.5g in morning (You'll have to experiment with doses. When you take piracetam, more acetylcholine is used up in your brain. Taking choline will replenish the lost acetylcholine that is used up quicker due to the piracetam. When you have the right dose, you won't have any trap or neck tension, no tiredness, no brain fog, and no headaches. It may take you awhile to get your right dose.)
--ALCAR - 500mg 3 times a day (You can up it to 1g 2 to 3 times a day if you like. You may notice more energy if you do that.)
--ALA - 200-300mg 2 to 3 times a day (Some ppl prefer to take R-ALA instead. It is, in a sense, more purer. If you decide to the R-ALA form, cut the dose I recommended in half)
--Multi-vitamin (Part of the basics. I use Now Adam.)
--Calcium Magnesium supplement (I believe all should take.)
--Fish oil (Good for overall brain and heart health. A must IMO.)
If you use centrophenoxine, cdp-choline, DMAE, or alpha-gpc (all which are better sources of choline than the others), you will have to lower the dose to around 300mg - 500mg. Again, you will have to experiment. Everyone is different when it comes to these things.
If you take all of these and find the correct dosages, it should help your studying tremendously. One problem is that some ppl don't respond to piracetam. Some ppl respond right away, some take up to a few weeks to fully realize the benefits, and other never notice anything. I, personally, find piracetam awesome. It is a theory of mine that the people that don't respond well to the racetams have elevated cortisol within their bodies. This will be a topic I will be bringing up within a few weeks. Until then, I hope all works well for you. After awhile of experimentation, you can add different nootropics to your stack. If you really get into it, it will turn into sort of a hobby like it has for me. A lot of things that you can add will elevate your mood. I find this diminishes the cravings for altered mind-sets from recreational drugs, tobacco, and/or alcohol. If you have any questions, don't be afraid to ask and welcome to ImmInst.