Make up help.?

so i wear a little makeup but i am bad at putting it on. i dont know what looks good on me. i know i need to buy some new stuff ( so if you tell me about a product have it be at most $20). i usually wear a little eyeliner and mascara and a tiny bit of concealor (but i have really dark circles that are hereditary and they do not seem to cover up). so please help me out in any way possible! thank you so much :)