@caffellatte a mixture of intervals, tempo, hills and long runs is a fairly standard plan for progressing. Examples:
Intervals: 10min slow run to warm up, 4x 1min intervals (run as fast as you can) with 2min recovery, then 10min slow run cool down
Tempo: 5min normal pace warm up, 10mins running faster than you normally would but not flat out, 5min cool down run
Long run 35-40 mins easy pace
Hills: 10min slow run to warm up, then find a nice steep hill 100-200m long, run up it fast then walk/ jog back down to recover. Repeat 5-10times then cool down
There's lots of plans on the runner world website. I'm working through one to get 5k in 30mins at the moment. You can also try the joy of fartlek!!