The ollie is the one trick in skateboarding which you need to learn first, as most street tricks are based around the ollie. It basically consists of jumping with the board. To start off, place your back foot on the tail of the board and your front foot around the area where the truck bolts are. The hardest part of this trick is the timing. First you should smack the tail down really hard and then slide your front foot up at the same time. What this does is 'pop' the board into the air. All you have to do now is keep nice and central over the board when in the air and then land with your feet spread out nicely and bend your knees as your landing. Practice this trick stationary at first until you feel confident enough to try it moving. You might find it hard to do this trick at first, but all it takes is practise and more practise. You might like to try ollieing onto the side of a curb while stationary, as this is good practise, or if you can do moving ollies the practise ollieing onto the curb, or over some small things, like cans or even drains.
Dropping Into a Half-Pipe
Before you start skating half-pipes, or vert ramps you need to learn to drop in, which briefly is when you put your tail on the coping, so the board is hanging over the edge and then lean in and skate down the ramp. It is best to learn to do this on a smaller ramp and before you try this its also best to just pump up and down the half-pipe starting from the bottom and getting higher till you are almost at the top.
Once you are used to this get up to the top of the ramp and put your board on the coping, with your back foot on the tail and your front foot towards the front of the board. The main technique of dropping in is the leaning forward. You have to be confident enough to do this, otherwise you will just slip back and end up on your arse. It might help if you just try and keep your front hand almost touching the nose until the bottom of the ramp. So as you lean in, put the front wheels down and push in. It is as simple as that. Then just go up to the other end and come back down again. After you have learnt these basics you can start doing some tricks on the coping.