Pros:
Strong early game
Strong scaling
Strong burst with headshot
Huge Range
Good self peel
High skill cap

Con:
Mechanically intensive
Sometimes banned
tempting to auto push

The first tree is straight forward. The secondary rune can either be inspiration or sorcery.
The inspiration tree gives you free boots and bisquites. It lets you spam q to harass and trade in lane. It also gives you boots to speed up the scaling. This is my personal go to secondary tree.
The sorcery tree lets you have a bit more damage with gathering storm and absolute focus. I don't like this one personally, as I feel it allows for less freedom with no mana and health regen.
Ultimately, it is up to personal preference.

The bread and Butter Combo is the EQ combo. E lets you net backwards, and q lets you damge the enemy. The cast time of Q is hidden in E. This is a good combo to get aout of any situations. A draven running at you? A talon jumping in? No problem!

Now it is more complex. It is the Headshot autocancel. If you trap under a guy, and e after, you will be able to get off two headshots at the same time. It takes a lot of practice, but it is really worth.

The third combo is EW combo. This let you net out while trapping the ground. This give you two headshots in the most ideal situation.

Another combo used in lane is the WQE combo. If someone gets hit by root, you can trap underneath them, q them in the face, headshot, net them, and headshot again. That is about 300-400 damage at least. It really hurts early.

In team fights, your damage are mostly from your traps. After you auto-attack, you immediately place a trap and then kite back. This will place a trap on the ground. In a messy fight, someone is going to step on it, and you are going to have a 1k damage crit. Be sure to work on this in practice tool. If done right, it almost doubles your damage.

There are four types of traps. The peel, the zone, the follow-up, and the random.

The most common use for trap is to zone. If you place traps on the jungle exit, the enemy would be forced to click around the trap, taking extra time, and giving time for your team to escape.

Peel is simple. If a Warwick is running at you, you can trap directly under yourself, and as he run through, he is rooted, allowing you to run away

Follow up is also easy. If someone cant move, such as in a zonia, or hit by a lux bind, or going trough GA revive, put a trap under them. They will get rooted immediately and take 1k crit to the face.

Random is how to trap in a team fight. You trap where the team fight is happening, and there will be a large possibility of someone talking over it. Even if only half ot the traps go off, that would be three thousand extra damage.