Remember when we talked about how to identify the right fit when job hunting? Well, believe it or not, this is equally important in the final step of the process as in the first: when you get a job offer, you still have to ask yourself if this is the best career move for you at this time.
Hopefully, you'll have had a productive round of interviews with your prospective new employer and followed up appropriately. You'll have screened the position first, of course, but you'll also have capitalized on the opportunity to meet the team and to get to know the organization to discover, inasmuch as you can, if you can see yourself working there. So, when you get a call with an offer, you'll feel prepared.
There's a sliding scale to what I'm going to say next; where you fall on the spectrum depends on where you are on your professional path and what shape your finances are in. But I think it's incredibly important to remember that, in most cases, your potential employers want to hire you as much as you want to work for them. They recognize that you're a good fit and they're excited to have you join their staff. What does this mean when you've gotten an offer and they're waiting for an answer?
Don't sell yourself short.
If you sense at any point in the process that the position isn't as advertised, you can politely decline. If you decide that it's not the best opportunity for you, you can politely decline. Or if you realize that your dreams are actually pointing you in a different direction, you can politely decline. But if it's right for you in every way, you should do your utmost to leverage the situation into a mutually beneficial acceptance. You know what you're worth - all the self-awareness that resulted from identifying the right fit for you, professionally, should help you define it.
Again, I'm going to point you to the experts, who'll advise you on how to do this firmly and graciously.
If you're not able to land where you want to, either because of your place on that balance or because of how heavily the organization is sitting on the other end of the seesaw, there are ways to make professional lemonade out of a lemons situation. You definitely deserve to feel good about yourself regardless! After all, you just got a job offer - and that's something to celebrate.