How to fit forks to fixie frame I have just ordered a fixie frame with no forks.

I will need to order a set of forks and cut them correctly (to the right size) so I can install my headset.

Are there any tips/ tutorials on how to do this correctly the first time and avoid having cut the forks tube too short?

thanks,
Park tool has plenty of information on how to do this, including how to cut a fork (and what tools are useful, namely a saw, a vise and a saw guide). They also have other directions, e.g. how to prep a frame for headset installation and what not. 

Depending on the tools you have, and how prepared the frame comes, you may want to leave some of the preparation to a bike shop (e.g. very few home mechanics are equipped to ream/face a frame properly).