If you're support and don't have a TP to rotate, you're not support. If you're support and there's a potential for a gank anywhere on the map DO NOT TP TO THE LANE; you need to keep your TP off cooldown, you fuck. This is such an important tip. So many times you can turn an inevitable death for your team, into a death for the enemy team instead. Fucking do it.
*If you're playing mid, early game and its past roughly 6 minutes, or you feel its right, CARRY AN EXTRA TP. It's so easy to get a free, granteed kill if you see an enemy dive a tower early game. (I've only turned this into a habit recently, and it's really payed off)
*Playing a carry and have no vision? Don't flame your supports. Vision is too important to go without. Buy the wards yourself if you have shit supports. Boohoo you lost 75-150 gold. Don't be a dumbass.
*Playing a hero who can get easy ganks and/or a support with a disable? BUY A SMOKE AND SETUP GANKS. More free kills and puts your enemy at a disadvantage. People usually wait until 30+ minutes in before they buy smokes. Supports can do this early on to gain an advantage. If you can do this early game and get a kill on mid, it's huge for your team.
Every time the enemy goes doom, i'll play jugg solo safelane. They never expect this. Never. You automatically win your lane, doom gets zero farm, and you are now a carry with a level advantage. PLUS this allows you to aggro offlane with up to 3 people in your off. Basically wins you two lanes automatically and it's super easy to be the one killing doom in your safe lane instead of him solo'ing you and your support with his level advantage. With spin-mode you are immune to Doom's fire and at level 1 you hit hard and have very fast right-clicks. This allows you to completely zone Doom out of lane starting from the beginning of the game and are basically guaranteed atleast 1 or 2 easy kills since you will get boots before him AND hit level 6 before him.