Short answer: Yes.
How else can you grow? Naturally this approach should be tempered with some self awareness of what you and your business ‘can’ and more importantly ‘want’ to do, but make “challenge accepted” your war cry!
Recently, an opportunity presented itself to me to support a large network client. It was a big job and would have certainly been a good opportunity for growth, however, the owner of the network was engaged in a pursuit that I found ethically questionable, so it was an easy decision to say “no thank you.”
So yes, if a project gives you a bad feeling, don’t do it. But if your reservations are just because a job seems large or left of field, why not try to see how you can do it?
Now that you are a little more courageous, what do you do if you have taken on something you previously thought was beyond your ability? Break it down into small, easy to do steps. Have a plan for each step, if you get stalled in the planning or execution stage, ask around for help. If you don’t get or like the help you are finding, ask more people, gather data, make conclusions.
Proceed. Above all else persevere. It will nearly always be worth it, if not for the task at hand, then definitely for the next time you do it, because once you’ve added that skill to your repertoire, it’s yours and you can go out and do it some more for others.