Thresh is an ultra versatile champion who adapts to any matchup, anyway I'll first explain what it's about.
His passive allows him to collect souls when minions jugle monsters or other champions are killed, which in the long run will give us armor and magic resistance.

Advice: do not kill yourself for the souls, it is a risk to go looking for them even more if we have to get very close to the enemy.

The Q is the ability that identifies this champion, passively the hook slows down and immobilizes the champion that we have hooked, also it has 2 actives the hook and the follow, use ir wisely.

Advice: you must be patient, do not throw it because you like the animation, the hook is the biggest threat, once it's on cooldown we are easy prey.

The W lantern, many adcs will surely frustrate ya, they'll surelly flash it XD. It is a simple but very useful ability, when activated it grants a shield to the champion reached and also if he clicks it he will come towards us, other uses are:

-TP

-Block a path

-To activate the guardian

Tip, W is useless if someone pings it.
E Flay, this ability allows us to engage or disengage, zooming in or out doesn't require much thought.

Tip, the E can be activated during the second cast of the Q and thus move more than one champion, it is also wider diagonally.

Finally, R, the box when activated summons 5 walls that when colliding with the first one does magic damage and slows down, the following hits will only slow down.

During the laning phase, two situations can happen:

A) Invade, here we will lvl up according to how far the enemy is. But as I said in the Q tip, thresh is a champion of patience, if we throw our best weapon at the wrong time it may cost the kill.

B) No invade, in this case it depends on the support on the other side and our adc, in the best of cases first the E, to accumulate magic damage and hit a charged basic that at level 1 does a lot of damage. (THAT'S A LOT OF DAMAGE)

Something that must be repeated in all games, unless we are against nilah or the enemy team has not given leash, is to prioritize getting to level 2, this is done with the first 6 minions and the next 3 melees. During the laning phase and until the first back you have to be patient, ignore the adc pings and engage when you see it's possible, remember not to throw your Q unintentionally.
On the first back we must analyze the possibility of Roam for this we must buy the boots, even if it is the level one, by doing this we will move quickly and be able to return to the lane at the same speed if nothing happens in between.
From level 5 and with the passive of the mission finished we must move around the map and help other lanes.

Thresh's Q has 2 actives, as well as 2 pulls. If we activate the Q as soon as the hook hits we will lose the pull, to avoid this first we let thresh perform the 2 pulls and then we will activate the Q.
Just like Nautilus, if thresh grabs someone near a thin wall then that champion will go through the wall, we can combine Q with E to make this an easier trick.
Regarding the R, I would say that you should use it all the time, but if a TF is comming, I would save it to throw it in the middle or closest to the enemy DPS