When you get into a manual, make sure you have one foot on the front of the deck but not touching the headtube, and your back foot on your brake, but dont use it. Only use it when you want to slow down and balance your manuals. If you want long manuals, go really fast and to balance it's sort of like humping the air, and try to keep the bars up as long as you can and dont even think about letting it touch the floor.
Trust me, it's going to help you a lot when you want to learn like double whip to manuals haha