Frustrated gambler advice

I have been playing online now for a couple of years and never did too well. Then about 6 months ago I decided to take my hobby more seriously. I have read a few books on no limit holdem. I was pretty amazed at how diffrent the hands played out and what I saw after spending some time investigating the game. I feel like I have a pretty good grasp on the true fundementals of the game and wanted to use the sit and go's to pratice, learn and gain experience.
One problem I find the lower limit games to be very hard to play. Everyone limps in, you will get called any amount at any time on a whim. Every hand has the possibility to be turned into a coin flip. So I moved up to some higher stakes tabels. I find these easier to play at but I am not really good enough to hold my own and could go through a good portion of $ playing there.

Any suggestions as to the best way to improve?