Honestly Black Arrow is not very good anymore. Unless they really changed something recently. I would suggest trap launching an Explosive Trap right away (unless other hunters are using it, because the tick doesn't stack) and SV hasn't been super great DPS since pre 4.0 MM is still the best by a good amount as far as i know.
But that probably won;t help your problem right now so I'd say you should never have full focus unless you REALLY need it such as when ES and BA(Trap) are off CD. While in between there keep spamming AS while you can and regen your focus with CS. Steady Shot sucks for any class other than MM and even as MM I would only use Steady to get that buff then its AS/CS because the CS damage is better.
Hope that helps.