Of course, if you put too many points into Beastmaster, you don't have as many to make yourself a kickin' Engineer. My advice:
1. Use the best gun you can
2. Wear clothes/jewelry with the best stats you can find
3. When you hit level 22, get yourself the best armor you can afford
4. Don't forget power-ups, buffs, and stims
Don't fool yourself, though. You'll never be a combatant. You'll be hard pressed to fight blue and even some green elites and you'll be overpowered by gangs of three or more. On the other hand, you probably won't be doing a lot of combat for combat's sake.
Finally, you're an Engineer. Why mess with beasts when you can craft yourself combat droids?