Makeup trouble

So I have gotten a lot better with makeup over the coarse of a year, but I still need significant help, how to use/blend eyeshadows, highlight, blush. I also need help with foundation I had a foundation that was too light for my skin so I got a darker one and it’s now to dark for the rest of my body (I’m anemic it has made me very pale so my face’s skin tone is lighter than the rest of my body) I l’have trouble when I put foundation on my neck because I don’t know where to stop and it looks weird if I do stop because there is a clear change in colour, any help would be appreciated also I need some makeup brands that are cheap/affordable that are of good quality and any tips or tricks would be great😃