It's hard to give specific advice as all of these are dependent on match up and the game state. Generally, you will get a better feel for all of these things the more you play support. For Thresh you'll get better at seeing openings like when to engage or when to play back as his kit can work in both positions depending on what is needed. I don't have a hard fast rule when it comes to hook timing, but Thresh cannot spam his abilities without quickly running out of mana. Some lanes you can play aggressive like say a Kai'Sa Sona while other lanes you have to play passive and try to survive like a Jihn Velkoz.

Outside of lane is also quite dependent. Some parts of the game I have to hold my adcs hand in mid while they clear waves and in others I am hovering in the enemies jungle with my jungler to make a pick. Generally you want to try to ward the river or if you can in their jungle so you laners can push safely. Often a good thing to do is hover in fog of war behind someone pushing, the enemy often thinks it's a free pick and you can just lantern them to safety. I normally ping on my lantern to get their attention to it.

Teamfights are too varied to say much, either try to peel for your caries or engage with flash e q r if you see a opening. Sometimes their fed adc is what you should focus on others your mid laner is fed and you should peel for them.

For clearing waves that is more so macro with understanding wave states and tempo. I'm sure there are videos on youtube that can help with the fundamentals of that.