save everything
Back your shit up too!
save everything
it may help you to think of the intro as a little summary of what is going to happen after the drop
in other words, someone listening to the intro should have a pretty good idea of what its going to sound like when it drops (that could be in regards to rhythm or a melody etc. obv leave some surprises)
and writing intros is a skill in and of itself. find a good tune similar to the one you're making with a good intro and fucking study that shit, break down where the individual elements get introduced, where things get mixed in/out etc
lots of detail and it will come together.
edit: also something i like to do is to have a rhythm (4/4 is fine) start at the very beginning (usually just hats going tik tik tik tik). the reason being is that it gives the listener an idea of the tempo. the same reason why films usually start with a shot of the location of the first scene - lets the viewer know wassup