The longer you wear a pair of shoes, the more they mold to your foot and become an extension of you. That's why old shoes are always the most comfortable. Every fold, flap, tear, slick spot and grippy spot all become just another part of your feet.
You know how when you buy a new pair of jeans, they might feel tight here and there, but after a little while they end up fitting perfectly? Shoes do that even more! Even the sole wears according to your feet, how you walk, where you put pressure... shoes really do become just part of you. That's why caring for your skate shoes is so valuable, and why people do pretty much anything (like use duct tape or shoe goo) to keep an old pair around!
So, if you're having a tough time with tricks after you get a new pair of skate shoes, don't worry! Just wear them around a lot and take your time. Wear them to school, work, out walking, and just do what you can on your skateboard. In no time you should be back to where you were before. And, you'll actually be better - every time you retrain yourself like that, your body learns more about how the trick works, and what to do. So, don't stress - just get out and skate!
Read Top 10 Skate Shoes for held with picking out a new pair!