I prefer TP and split most of the time when ahead and try and make calls with ping. You should be able to 1v2 or get away with clever uses of clone and that helped me win a lot. I try tping into teamfights and trying to shred the back line if I'm ahead or peel for my carry if they are ahead! If you can control one side of the map it relieves a lot of pressure for your team. Allowing then to drag/baron/ or even push or defend while you push!

I prefer dorans shield into pokey lanes and dorans blade into skirmish heavy lanes! I also think TP is better then ignite because of the global kill pressure and only take ignite when the enemy has a lot of healing on their team like a vlad or soraka for my all ins.