Practice!

You've probably heard it from mjifi, but everyone should do the 80/80 challenge and do at least 70+ last hits. It's simple, go mid with a ranged hero without any points skilled or items then try to hold the creep equilibrium while getting every last hit/deny. That means you shouldn't be pushing the wave into either tower.

Also, if no one of you have a better idea then this is a casual day where you can practice whatever. Playing pubs or just doing challenges. It's important however that you have training in mind and focus on what you're trying to accomplish when you're practicing. If you're playing a pub and your goal is to last-hit then keep it in mind. If your goal is to gank and coordinate, keep that in mind.