Look over your splits, if you are positive splitting you are going out too fast, and if you are negative splitting by a lot, you can afford to go out a little harder. This alone can shed some seconds.
If your mileage isn’t already more than 35 a week, get it there.
Any repeats 400-800 at mile pace seem to yield good training results for the mile
If you have a sub 5 guy racing against you in a meet, hold with him as long as you can. You might end up embarrassing yourself but it’ll show you what you are currently capable of and will start forcing your body to adapt.
I’ve made a jump from 4:50s to 4:30s and hopefully 4:20s this year! Good luck!