It kind of varies with me, but I usually start with a chord progression/bassline, then build off of there by doodling in the piano roll in FL. The process is a bit time consuming due to my lack of a midi keyboard, but I manage. When I start my project, I normally start with a piano, using a very simplistic melody over the chord progression I made, then I start adding more instruments, making the melody a bit more complex as I progress in the project, tweaking things as needed.
I usually also have a set "feel" I want the track to give, be it with the key signature or the way the melody plays over the bassline.
I normally don't try to do this, but my songs almost always end up with a trance-y feel to them, but I do try to start with a neutral genre and let my mind take over from there, ending up with trance, as it's what my mind tends to want. But lately, I am trying to venture into new genres and make tracks specifically in the new genre, House being my main attempt atm.
It's kind of hard to describe my process, but in a sense, I start with the feel, make the chord progression, then turn my focus almost solely to creating the melody and making it great. Everything else just follows suit and isn't as much of a focus in my mind.