You always wanna save your mana on using q on cs , or using it against your enimes you always wanna use it mostly in farming / last hitting with it , You can poke with your q and last hit with meele attacks wich can be dangerous against High poke champs : teemo , quinn etc...

Its always up to you but GP if played right counters almost all top champs

GP has a really great laning phase , he has the heals and the dmg wich makes him really practical, wich leads to never leaving the lane wich is a good thing against great pushers , you always wanna help your team mates with your ulti specialy in mid if their jungler went to gank your teammate in mid , NEVER waiste your teleport use it correctly and not stupidly , Wards Wards Wards... , Save your life with wards , ward the river and bushes around you since you have no escape ability but your flash

Pros
Great Laning phase
Has a great heal
Great poke
Can build so fast
Practical champion
Can help teammates with ultimate

Cons
Has no escape ability
Always depending on Wards
Has no great cc But hes slow from hes ultimate
Depends always on hes cs / Gold
Weak DMG early game