Hi, Mick.
Especially lasers produce a lot of heat. And the heat increases exponentially to the speed of draining the WEP energy pool. (As the pool drains, the guns bleed more and more heat into the hull. With empty pool it overheats your ship almost instantly) So it's a good idea to shoot only through the first half of it and then let it recharge and cool down. Also it's best to shoot lasers always with 4 pips in WEP.
Better powerplants have better heat dissipation, so they help, too.
Also you can try a mixed loadout. Especially multicannons are very good. You can shoot them while your WEP is recharging and lasers cooling down.
Then again, it also comes down to a ship you're flying. Fer de Lance, for example doesn't overheat at all, while in an Imperial Eagle you spend most of the time above 100% by default.
