Your positioning in the surf break is one of the most important elements of learning to surf and practising to catch a wave in control, is the best way up-skill. Once you have mastered this, you are ready to try standing up.
Firstly you need to ensure that your board is racing down the wave before you prepare to stand up. Place your hands on the side of the board to either adjust your weight back to avoid nose diving, or with the same hand position, hold the rails to jump up onto your feet in one swift action. As you are already in a falling position, the momentum is there to stand up.
Although some beginners like to get onto their knees first this is really a lost opportunity to ride the face of the wave.
You will probably fall off many times, however by doing this you will learn to place your feet in the correct position at the back of the board. Bend your knees to enable you to start turning, ensuring that your head is positioned over your feet, before trying to advance into radical turns.