From working in child care for many years, I know this can be a difficult time for parents. It is often harder on the parents than the kids. Not sure if the baby has started child care yet or not, but if not, spend some time with your baby at the day care together. Get to know the teachers and other babies/parents in the room. Learn how the care givers respond to infants and how they interact. This should give you some more peace of mind before you start. If your baby has already started going, spend some time there when you pick up.
When you drop off in the mornings, I suggest holding your baby while you put things away etc so your baby can have a few minutes with you once you are there, then give hugs and kisses and say good buy. Never sneak out or leave without saying good bye. Make it into a routine and do the same thing every morning. This will provide consistency, predictability, and reassurance for your baby. The longer you linger and act hesitant, the more unsure your baby will be about staying there. If you act confident and cheerful, your baby will feel more secure. If you want to stay and play in the room, do it in the afternoon/evening when you pick up.
When babies/kids are in child care at a good center, it can be a wonderful experience. They are able to interact with others at a young age and learn valuable social skills. They do activities that they may not otherwise do at home. They learn confidence and self-help skills. The list goes on. Point is, please don't feel guilty for leaving your baby or let anyone make you feel guilty for not staying at home. This is your decision and as long as your baby has loving, caring teachers, everything will be fine. I do encourage you, though, to really get to know the care givers and spend some time there to get a feeling of how things are done. Don't be afraid to make requests on how you want things done for your baby.
Best wishes!