A complete skateboard is pre-assembled - it almost rides right out of the package and on to the streets, ready for you to practice all your new tricks. You simply don’t have to think about buying the separate parts like trucks, wheels, decks or the likes. Once you have gained more experience on the board and you feel like customizing it to fit your skateboarding style, you can begin to learn more about the different pieces in order to assemble a skateboard that meets your specific wishes and demands. Until then, a complete can be quite the right choice.
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.