You could also try looking at your front wheel while learning to manuel. If it's straight you'll go straight, and won't veer off to one side. When it comes to your "sweet spot" also known as your balance point. I learned how by not yankin up on the front end. Just try to lean back and keep your arms and knees slightly bent. From there you can position yourself to compensate for balance. Trust me though, once you find your sweet spot, it will take a long time to get yourself into a rythem. I've been riding for eight years, and I still have yet to get it everytime. I don't really think there is a rider alive who can get manuels to go thier way everytime. so just try different things, and remember to have some fun with it. you'll get it eventually, and if you become frustrated, take a brake.