I definently notice i go in an ebb and flow with what i make. I started with 10 bucks and got up to 200 in like 3 days... then i blew it down to 50, got up to 200, down to 100, up to 300, etc. etc. up to 480 and now i'm at 410 and climbing. i play at .25/.50 even though my BR can't quite afford it according to most advice, because i eased my way in and am comfortable there. i've lost down from 400 to 350 about 4 times, a 50 dollar loss wouldn't phase me, and its not like i'm going to lose 7 buy-ins to bust out totally. just play at a level where you're comfortable and a streak of bad luck won't eat your whole br.

moral of the story - in my experience, you will probably do well at points, and lose a lot at other points. best things you can do are don't get overconfident when you win, don't move up in limits after a big run as you'll just go AI and lose it all too fast, and expect to struggle for a while before you win.