Help! How on Earth Do I Go About Finding a Nanny for When I Go Back to Work??

Start with referrals, if you can. If you know anyone else with a nanny they love, that nanny may have friends. Those are your best references.

After that, I have several friends that have found their nannies through:
sittercity.com and care.com.
I've used both for finding babysitters, myself, and have had great experiences. Both sites require background checks.

If you would like, I have the nanny contract and interview questions that we used to find our nanny. PM me your email, and I'd be happy to pass them along to you. Both were written by lawyers that are friends of ours.

We've had our nanny for 6 years, and we love her!
If you find the right fit, she will be critical to your life and become like part of your family.

If you can arrange to have a spare bedroom available, the best bet is to have an au pair. We found that the available hours, convenience, cost, and the background checks, made it possible for us to be confident that we had secure child care. Having an au pair, that you choose from interviewing candidates from their profiles, you can find someone that will be the best fit for your household. Check on line, there are about a dozen US registered firms, the prices are basically, about the same (some have special sign-up discounts), and Tax Deductible. It will cost less than hiring an unknown stranger from the neighborhood, or from Craig's List, and you can have more confidence that the person has gone through the background check. Not all au pairs are "infant certified", but their profiles state whether they are. Look for one with several younger siblings, and over 21 (I think they start at age 19). They are all required to pass an English test, and have a driving license valid in their country. We did it twice (their visas are valid for one year with a second year extension, if mutually agreed). At least check into it.

If you can afford to stay home and put your career on hold, you might consider doing that.

If you can't afford it, or feel you wouldn't be happy as a SAHM, then you will have to hire someone or place your baby in a licensed child care center.

Do you belong to a Church. That might be a good place to start. Check the Church bulletin or even place an ad in the bulletin yourself. You can also place an ad in your local newspaper. Interview as many people as possible very thoroughly and get references. Make your wishes and expectations clear. Ask very specific questions to make sure her viewpoints align with yours. If the candidate is older, make sure she is up to speed on current recommendations (laying babies on their backs to sleep, no stuffed animals in the crib, keeping the temperature in the nursery cool, no table food until six months etc...)

Good luck!

Call an agency or something.

I gave up my career, so I have no experience hiring help. In fact, besides my parents, and one friend, my kids have never been left with a sitter.

I'd ask around at work and see what other people do. But there has to be a quality agency that will send out candidates.