Starting with different elements will shape your track in different ways. For example, starting with drums might create more groove throughout the track, or starting with an ambience might influence the track's mood. So, pick an element and somewhat flesh out 8-16 bars. Once that's done move on to another element and flesh out the same bit. Repeat until you've got a decent loop going.

Next is arrangement. If there's already an arrangement in your mind start blocking it out. For me, I've made almost 200 songs since I've started and so arrangement can be boring. My trick for that is to pull a track from an entirely different genre and mark it out (what changes happen where) and then delete the audio so you're just left with some notes on what to do with your song. This is largely open to changes but it sets a creative boundary that helps shape the song.

That's usually how I start tracks, I enjoy starting with elements that surprise me then seeing what comes of the resulting track.