If you want to curve the path of your ball to avoid an obstacle or move it out of range of the goalkeeper, sidefooting with the outside of your foot could be a good solution. It helps you find different shooting angles for your strong foot.
As a reminder, your strong foot is the one you feel more comfortable shooting with, while your weak foot is the one your feel more comfortable kicking the ball anywhere with.
The main thing is that you kick the ball with the outside of your foot to send it spinning: the path of your ball should curve. From left to right if you kick with your right foot and right to left if you kick with your left foot.
You need to remember two technical points to surprise everyone with a well-practised sidefoot kick: the position of your supporting leg and the kick itself.
We'll start with the supporting foot, which is the foot you don't plan to shoot with (and in the case of an outside foot shot, even when you should). Place your supporting foot about twenty centimetres behind the ball. The inside of your foot should be in line with the left-hand edge of the ball if kicking with your right foot, or with the right-hard edge of the ball if kicking with your left.
For the shot, you need to aim for the centre of the ball with the outside of your foot. You might have guessed this from the name of the technique. To give your shot enough power, you need to kick the ball with the front part of the outside of your foot. If you don't, you'll spin the ball too much and lose power.
In short, if you want to make the ball spin outward, or if you prefer to try your luck with your strong foot rather than hope for a miracle with your weak foot, set your supporting foot 20 centimetres behind the ball and kick with the outside front of your foot to give your kick enough power.