It does take some practice, but you will soon be able to get in and out of most gas stations without problems. I also drive a 32' Class C, and I DO try to use larger gas stations on the edge of towns. The big ones like Love's or JA, etc. tend to be very easy and also have some parking if you want to run inside for a snack.
You do need to: 1) check the height of the canopy if it is an older station, 2) use an outside lane if possible, and 3) drop your mirrors a little as you drive in and out so you do not scrape the side of your RV, and 4) most importantly, as kfdgoat pointed out, check to see if the curb has a dip so you do not scrape the bottom of your rear end leaving. (This is true also for shopping malls and other parking lots.) Most larger Class Cs have a lot of real estate behind the rear wheels which means they occasionally drag, making a horrible noise. (Check out the scrape marks on the asphalt before you drive in.) Also, they have "tail swing" which means that your tail moves to the side a couple of feet when you turn in the opposite direction.
Most of us get in the habit of doing a quick scan of a place before we drive in. Occasionally, I will even drive by and circle the block to check out whether I can get in and out of a gas station. And if you are alone, as I am, and you get stuck or are unsure about how to get out of a tight space, just ask someone to help direct you.