Creating an outline
There are a few ways to do so in hitfilm. However I dunno if there is a best way. I had been using a newblue effect called outline, even though it did exactly what I wanted it would sometimes lead to stability issues. The new outline option in the text tab works well for text sometimes but othertimes eats into the font and doesn't look good. You can make one but expanding a mask sometimes.
So another way I have recently started to create an outline, which works good for text and for images is I take the outer glow effect, I bring opacity and spread all the way up, and then I make the size whatever I want. This generates the same effect as the newblue outline effect did except I haven't had any stability issues doing it this way.
So, try it if you want, or don't!