everyone talks about stacking, stacking is useing more than one supplement at the same time to increase effects. but the question is wat do i stack? i here the most common is a multi vitamin, a protein shake, creatine, and bcaa's/eaa's <<<what ever that is

. ive looked up these items and theres tons of different kinds! what to buy? wich is safer which is more effective and wats cheaper? i know i aint the only one that aint got very much money.
Multi vitamin- which "multi vitamin" has more vitamins? and again wats cheaper
Protein shake- is it easy to make youre own? is it cheaper to make your own? if it is how do you make your own? if it aint which brand should i buy?
Creatine- again what brand? its all the same aint it? is it cheaper to by the 100 grams er 500 grams er wat?
Bcaa's/eaa's- WHAT THE HELL IS THIS!?