Land at the same time – Again, this is probably silly to repeat, but you’d be surprised to find out how many people execute a successful jump, and then throw their hands up in the air to celebrate their new-found triumph, and forget the most important part: landing. The best position for your feet to be in is as close to the trucks as possible. Don’t land too close to the nose or tail, or you could end up breaking off those the board itself. Also, remember to bend your knees to absorb the jump. Don’t want to land straight-legged: that’s how kneecaps are destroyed.
In 1978, Alan Gelfand, who was given his nickname "Ollie" by Scott Goodman, learned to perform no-handed aerials in bowls and pools using a gentle raising of the nose and scooping motion to keep the board with the feet. There are numerous references to Alan Gelfand's Ollie with most notably pictures in the 1970s skateboarding magazine "Skateboarder".
Go for the low truck profile if you want to obtain additional stability when you do flip tricks. It also works well for small wheels. The mid-sized trucks are good for all-around use, especially in streets and parks. You can also choose the high-sized trucks that are good for carving and cruising, which is the reason why they are perfect for huge wheels.
To get higher ollies, I would suggesting resting your back foot on the very end of the tail and the front foot in the middle of the deck to allow for more slide. Popping as hard as you can and catching your board in the groove of the nose with you ankle practically resting in the groove will level the board out in the air. after this initial movement slide you feet back to the bolts on the tail and nose to ensure a clean landing.