I play a lot of mid lane and with that comes a bunch of roaming. When is it a good idea to follow your enemy laner to other lanes and when is it smarter to stay in lane? I know there is an extreme amount of variation on reactions based on situation so please explain any of your reasoning.
Base on what champ you are playing.
If you are a 
or 
, better push your lane as hard as possible until your core items complete. Because you have nothing really effecttive to help your team mates. Just punish the roamer by push his turret and farm wraiths, wolfs.
If you are a battle mage 
or an assassin 
, better follow your enemy or go to another lanes looking for gank chances.
The most important things are wards and pings. Your map awareness will help your team mates know when someone coming, and have their decision about remain in lane or retreat to safe place.
Edit : Even if you want to follow enemy, try push your lane toward enemy's turret. Because if he miss the gank, he will also miss CS.
play tf have global presence no matter what. win.
