Job Dilemma

Recently I had an opportunity to apply for a job that I had a decent shot at getting, but I was unsure about whether it was a good idea. It was for a receptionist at an acquaintance's business, a business that I patronize. I really wasn't sure if I was the right fit for the job, so I was very conflicted. What if it didn't work out and it damaged the relationship I have with this person and this business (it is a veterinary clinic)? I have been looking for work for six months and maybe it's stupid to not go for it...in the current job market is it a bad thing to blow off a potential job opportunity just because things are complicated? I have a feeling that this question will start coming up more and more in the future.