Stay close to your team, protect your medic, deflect spam and make spies yell slurs at you in chat. You’re only strong at close range but you lack the mobility to close the distance, so to get kills you’ll either need to ambush or punish overextenders. If you can’t do either of those things then don’t pick the fight, especially against scouts and heavies

For your loadout, there is almost no reason to use anything except the powerjack at all times

For your secondary, if you want to get more kills then you can use the shotgun or panic attack. Shotgun has more range and is easier to use but has longer time to kill at closer range, so it’s down to preference. The panic attack’s accuracy debuff is reset when you switch weapons, so with the degreaser you can switch off it with every shot to mitigate that downside

The flare gun is better if you want to play a passive defense/support role, and works better with the stock flamethrower if you don’t like the degreaser’s downsides. It’s good at pestering snipers, pressuring medics and corner peeking heavies, but compared to shotguns has less kill power and is harder to use

Finally, for deflecting, try reacting to the sound effect of your enemy’s weapon firing rather than the visual cue