Make up problems any idea?

So i dont usually wear a lot of make up my every day make up its just mascara & eyeliner. But i do wear foundation like once a month if even if i have a event to go. The one and only time my foundation looked good was when i got it done at Sephora the girl was looking for my shade so she applied i love the one from urban decay naked i have that. But when i do it it looks cakey it turned different color l do do exactly like i see on youtube i have a little dry skin so i scrub than i use moisturizer. I apply the make up correct i dont understand what i do wrong lol sorry just so annoying