As a Childcare provider who finally let my own children have a babysitter outside of the family I know what you mean (my "babies" are 3 years old). Here are some "inside tips" that I would use if I had to find a provider.
I would suggest you use word of mouth, and do your research. If you go with an in-home daycare make sure they are licensed and not just registered. Also, call Childcare Resource and Referral and ask for the providers in your area. When you get the list if any of the providers in your area are accredited they should be at the top of your list. Accreditation is a 9-month long process, and pretty intensive.
When you interview, ask questions about why they have an opening, how long have their families been with them and if you can get a reference of a family that is no longer with them. See how long they have been doing daycare, if it's less then two years use your gut, the greatest amount of providers that quit is within the first two years. How many training hours above the required do they do? Are they involved in any daycare associations? Watch the way the provider interacts with your baby and with other children. Are you interviewing on the floor or at a table? Does the provider want to pick up your child, does she ask or just grab the baby? You should have a good gut feeling by the time you are done with each interview. Also, taking another mom or grandma with you can help be an extra set of eyes and see what they think.
For centers look for ones that are also accredited. Ask them questions about their staff turn over rate as well as their family turn over rate. Also, look in the corners and the toys closely to see if they look clean. Are the children clean or do they have messy faces. Ask to see the eating and napping area. Don't be afraid to get down at ground level and take a look around, it's a completely different view at the floor.
In both cases you can also contact the County Social services to see if any of the programs you are looking into have had any violations, ask for details to see if these are serious or if they may have been from a disgruntle employee/family.
I know this is a lot of info but I hope atleast some of it is helpful, good luck. I hope you find someone who will love and care for your baby as much as you do.