In lane you need to stay in the bushes and jump on each minion with your Q to grant stacks when u got the 5 stacks you can poke with the golden Q.
In lane you really need to farm , this build is expensive and you wanna get the core as fast as possible . When u got the core items you are ready for teamfights.

In teamfights you gotta stay a little bit back like not in front with the tank/s but in the middle line.
When the fight starts you wanna have your ult on so get it right and try to one shot the adc/mid laner or other heavy dmg champs to make the fight easier. After you jumped and killed whoever you killed you are most likely to be focused so I suggest you to buy the "Guardian Angel".

So before teamfights when everyone just walk around and farm a little bit you wanna try to ward the are so you can maybe catch someone with your ult in the jungle like the CAT needs to do .
If you do succeed you got yourself and your team a great advantage.
When you feel free you should try to split push before someone comes and quickly destroy a turret. Thats when the warding stuff matters and thats why I do not suggest buying the farsight because its not really a ward it is just a one second far vision for a certain area and I think that the normal wards are better for this build.