3 things.
1st - make it part of your life. Play every day, just 10 or 15 minutes, but make it habitual.
2nd - Songs songs songs. Learn to play your first song all the way through as soon as possible and then add to it with more songs.
3rd - Keep it fun. Find what is your groove and do that more than anything else. What ever it is that brings a smile to your dial.