Up until recently, would just focus on getting the song down in various styles, without writng it down.
But now I write the stuff down, because sometimes I can come up with some nice fill-ins & forget them the next minute

For that reason, it helps to have it down on paper (not that I'll ever play it as it is on paper again--i go by feel.)
But each time I'm practising a song I have specific focus areas, viz:
1) Getting familiar with playing the song in all the keys.
2) Analyzing patterns prevalent to other songs I know of;
3) If I don't readily associate the pattern with other songs, I try to THINK of a song where a particular pattern can fit in.
4) Most often than not, I compare the sound of the same chord in different inversions &/ I compare a chord with other chords for a specific part so that I have various chords to choose drom for 1 part.
I don't play at church so I don't have too much pressure on me, however, I'm planning to play the synths as soon as we update our sound system/ equipment..