Earlygame
The first thing we chose to do when the game starts is the invade, we'll always invade botside for a chance of an early first blood. Which will lead to:
The enemy side losing their motivation, likely feeling like the game is already lost. Also leading to your team getting a 400+ gold lead.

Red side(easiet invade):
Start off with going into the bush next to the pixelbush in botside jungle. Checking if they'll invade or check. If not go directly go into their side of the jungle. Where they will likely be waiting. This will most often lead to a kill or a teamfight were you have the advantage.
Important: Always start with Q if your team agrees to invade.

Blueside (more difficult):
This is the more difficult where they'll get information early if you're invading. Hence we will invade by going from mid bush. Hugging the walls (even though they'll likely see). Where you'll check every bush until going to the Bluebuff. Where you most often will find: Jungler, Support and ADC.

Laning phase:
During the earlier part of the game, your mission is to keep vision up, push the lane and poke as much as possible. This is to keep the control of the lane so you can start roaming after you've gotten your mobility boots. Where the mobility boots will help you being mobile during the earlier game so you can help mid and jungler if a fight breaks up.

Mid game:
During this phase you should start considering going to midlane and start pressuring and wait for a missplay where you can easily get a kill. Keeping control of the lanes (waves pushed) you can consider taking dragon and herald. Which will lead to control over the game.
But when should you consider leaving your lane?
I would only recommend leaving your lane when your ADC for example Draven has gotten some strength and items, usually first item like . Where as he's usually capable of farming by himself at this part of the game.
When your ADC is capable of handling the botlane all by them selves theres not much to do there. Therefor you should start roaming and focusing on Mid and Toplane.

When to fight:
First off. Don't start any fights when you don't have the advantage. Fighting when the enemy team has the advantage most often leads to your team losing, which will lead to more consequences like them taking objectives.
You should only fight if:

If your team has the number advantage.

What does it mean to have the advantage? Usually your rule of thumb is that you have 25% more kills in the Mid game ~20 minutes into the game. OR someone in your team has been winning their lane pretty big which will lead to them having a greater damage output during the fights/teamfights.

If any enemy do any missplay where they are in the open where you can get a free kill.

For example, their support overextends leading to you Thresh being able with your viable kit to punish them for overextending.

Tips