During the early game is where you are at your strongest. Sett deals a lot of auto-attack damage with his Q and his E makes it impossible to get CS if you go in, due to the stun.

This allows you to snowball ahead in kills and minions while your opponent is in the dirt

If this does happen, keep an eye out for jungle ganks. If you're snowballing whilst your other laners are not, it will be likely that the enemy jungler will gank you.

If you are ahead, you should be fine so long as you don't take unreasonable trades. Going up against your opposing top-laner and a fed mid-laner is not the best idea

If you're ahead during this phase, you should have secured your lead in top and should be looking to help jungle and mid lane

During late game is where you need to be careful. Blindly running into fights, no matter how strong you are, will get you killed.

If your team can handle themselves without you, look to split push a lane during a team fight so that you have the advantage. If not, join the team fight and help your team come out on top

Sett has a variety of power spikes

His level power spikes are levels 2, 3 and 6

Level 2 is when he gets his E and can punish overextending, allowing him to get significant damage

Level 3 is when he gets his W, allowing him to get a massive shield during a fight

Level 6 is when he gets his R, giving him significantly more kill power

His item power spikes are when he gets Blade of the Ruined King and Trinity Force

Blade of the Ruined King allows him the upper hand in chases with the ability to slow the opponent

Trinity Force gives him a minor boost to all of his stats as well as Spellblade, which increases his bsaic attack damage after a spell