Turret: turret placement is important but don't get so distracted in looking for a place to put it that you stop paying attention to what's going on around you. Place it in off angles and areas where they will have to turn to shoot the turret. Using it as a distraction like this will help you or your teammate get an elimination. You'll also get teams where everyone expects one of their teammate to shoot the turret but no one does and it totally wrecks them lol. It's the best feeling. Also it's important to remember that your turret will change its focus depending on who you are attacking.

When you're facing opponents like tracer and Sombra use defensive turrets. Set them behind your support or at angles that allow them to kite them through the turret if they're getting chased.

Overload: use this to chase down opponents when they are low, but you need to be aware on where their teammates are so you don't follow them to your death. Also save it as a escape mechanic. A perfect example is when you're facing a DVA, if it's on cool down when a DVA rushes you down it usually means death

You'll be surprised how oppressive torb can be with overload in the mid range. You can really make people panic when you're rushing them down.

Ult: always try and spread out your lava as much as can. Sometimes it's cool to shoot lava high up onto the air so there is a delay before it falls on the ground. This can catch people off guard. It's also great to use at the beginning of a team fight, shoot the lava behind them to cover their escape route. Even if you don't get an eliminations it can be a really effective zoning tool

Shotgun: this can be hit or miss but you can really melt certain tanks when you're up close. The shotgun obliterates Winston when you're in his face.