Your HBS is as valuable if not more so than your CAR15. This little puppy should be carried everywhere, period. Learn how to use it, quickly and effectively or live your life as prefire bait. Know every ICP and bottleneck, know every little quirk about every map. Know your routes so you don't even have to think about doing it, you just do.
Speed is essential at the start.
You can slow as your approach hostile areas. Use conventional tactics only half of the time, come up with new ones as fast as people figure out ways to counter, try not to repeat a tactic over and over. Just don't be predictable. If it looks good on the outside, it's rotten to the core. Knowledge is power as the saying goes.