First is not actually a cheat/tactics, I use Logitech G600 which has horizontal scroll which is 2 extra buttons on tilting the scroll wheel to the left and right, basically it is used for navigation when in file explorer or web explorer. I set these 2 buttons as Next Unit and Prev Unit under Control Groups Settings, gives easy access to cycle through summoned units. Really helpful while playing meepo (next,poof,next,poof...), lone druid or warlock.
Second is a trick that I started using few months back when many would pick Zeus in pub, carry Smoke of Deceit and use in case you have low hp and Zeus has his ultimate active, easy counter.
Edit: Gamer ID : 10448596