I got my BH start in a Viper mk.III as well, back when I was a complete novice at outfitting, but I managed to get by pretty well with twin small gimbaled cannons and twin medium lasers (can’t remember if they were pulse or burst off the top of my head, I’ll check later). I didn’t engineer much because, only a month out of the gate, I honestly didn’t really understand it yet.
2.5 years on, I’d recommend a mixed bag of kinetic and thermal weaponry. Twin medium PAs would be pretty good, plus twin small MCs with corrosive shell. Spare no expense when it comes to shields and thrusters, and definitely add an MRP for when it all goes horribly wrong.
As for the next step past the Viper, you really can’t go wrong with the Vulture as already mentioned. Give it a large PA and burst laser and it’s lethal to just about anything. Just be aware that the Vulture is somewhat short on power, so engineer the crap out of the powerplant.