But, practicing too much on grass is lazy and can give you bad habits. If you practice on concrete and you do something wrong, you will fall and get hurt, right? But on grass, if you do something wrong, the grass will catch you and help keep your stable, and protect you if you fall. So the problem is making sure that you don't get addicted to the safety and comfort of practicing on the grass. You need the pavement to help you by being unforgiving, and you need to fall from time to time, so that your body learns what to do.
So, the key is to make sure that you don't practice on the grass too long. Using the grass is great, but you should alternate, and try and practice on the pavement or concrete, too. Switch back and forth, and slowly work into only using the pavement or concrete for a certain trick.
The same idea applies to practicing tricks while rolling or standing still - if you always practice a trick standing still, then you might develop a bad habit or two that will mess you up when you try it rolling. So, you should try the trick while rolling, every once in a while at first, and working up from there.
Breaking Bad HabitsSometimes you might have practiced a trick a lot on grass or a balance board or something like that, and now you have a hard time on concrete, and you don't know what to do to fix it. Well, the answer is tough, but easy - you need to start over from scratch. Put your skateboard onto some pavement or concrete, and just try the trick. You will have a hard time with it, and you might get hurt, but keep practicing.
You might find it helpful to try a totally different trick for a while. If you've been learning to kickflip, and are having a hard time with that, then try learning to pressure flip or heel flip, or whatever. And practice alternating between on grass and concrete. Doing something totally different should help your brain and body to reset a little bit. If that doesn't work, then take a break and do something totally different, like riding ramps or longboarding.
But, the main way to break bad habits is to practice doing things the right way. Start from scratch and re-learn the trick. If something doesn't work, then tweak it and keep trying. Just don't give up, and take it easy - stressing over it doesn't help. Relax, and make sure you're still having fun!