this is just my op....but,a good start 0f supps would be creatine, whey protine drink, multi v.
your only 20yrs old so you are making good amount of natural test. you should be taking in the amount you want to weigh in protine(1-1.5 g per body weight) .. ie, if you want to weigh 180lbs youd want to take in roughly 180-270 grams of protien . carbs are i belive (1g per lbd of body weight) but if your young and thin and have a high motab i wouldnt worry so much about carbs and fats. as long as you eat clean.
you should be eating as much and as often as you can preferably 6-7 times a day. a meal replacement drink might be good as well if your schedual is tight. eat lots of protien packed meats like chicken ,tuna, steak ect. salmon and other fish have good fatts that youd want to take in as well.
your multi is your foundation, its gonna give you alot of the vitamines an minerals that your body an muscles need to grow and maintain them selves. think of your body like a steak ... if you were to eat a steak what part would you eat first? the meat or the fat around the meat?...the meat right? .your body is the same way, your muscles have all the nutrients ,vitamines,and minerals to keep you going, and if you dont have plentie of vitamines,minerals ect ect your body will take from the first thing thats easiest to get all that from...your muscle. fatts take too long to be broken down and turned back into what your body needs at that moment.
the creatine is more or less a transport for everything you feed your body to your muscles. it floods your muscle cells (or volumizing them) with protiens minerals ect. just making the cell bigger to hold more food, so that the enitre muscle can grow.
your protien shake is just food for your muscles
a meal replacement shake is good for tight sckeduals ,and geting those extra cals that you need .
as for your wk outs ...dont over train yourself and allow recovery time . if you dont or havnt been working out for a long pertiod of time you should be able to add muscle mass fairly easy.
if i was you id stay away from dairy products befor and after your wk outs and even in the morning when you first wake up.. dairy is hard for your body to process, and before and after a wk out your body need quick fast acting protiens/food. when you first wake up you are also in a state of replenishing your body. so make it count give it what it needs to kick start your day.
hope some of this will help.
garryb