If you are returning to work after maternity leave, it will feel like the worst decision you have ever made. Even if you love your job. A lot. This is normal. You are not a bad mommy for going back to work. As long as your kid is in a great place while you are at work, everything will be fine. It will get easier and soon it will just be what is normal.
If you are returning to work, your first visit to a prospective daycare will be overwhelming. It is a lot to take in, thinking you have to leave your perfect baby with an imperfect stranger. You will probably cry. Don't feel bad if you need to leave and reschedule. You won't be the first, or the last. I cried like a fat kid with no cake after visiting our first daycare.
Don't return to work on a Monday if you have the option. Having to think of an entire week away from your baby is too much. If you can, start back on a Wednesday or Thursday. You can make it two or three days before a full weekend with your family again. You cannot make it five.
Before you go back to work, take a day to get yourself back together. Get a mani/pedi, get your haircut, buy a new outfit. You will feel like you are totally a fish out of water when you first re-enter the pond, but at least if you feel like you look good, you will have the confidence to jump back in and start swimming. Try not to show up for your first day in your maternity leave uniform: yoga pants, a puked-on t-shirt from your college days, slippers and a ponytail. People tend to frown on that. Whatever.
The first time you drop your baby off with their new caregiver, schedule a lot of extra time before you need to leave. There will be a lot of crying, on your end. A lot. It will get easier. Give yourself time to be with your baby in their new place and talk with the people that will be taking care of them. This way you will feel like you are not just abandoning them. Also, bring make-up with you so you don't have cry lines in your powder and smeared mascara to start your first day back to work.
Once you get to work, feel free to call and check in on your baby immediately. The people at your daycare will not think you are crazy. It is ok to call seven times on your first day back just to, "See what your baby is doing." If your daycare starts to get annoyed, that is their problem. Most likely you are paying them an arm and a leg to do a job that you would love to be at home doing for free, so it is ok to call and check in.
The most important thing to remember when you return to work is that being a working mommy will not result in your child being a loner weirdo with mommy issues who enjoys killing cats. Same applies to you SAHMs who worry that your kid isn't getting enough interaction with their peers. They will all be fine. We all do the best we can with the cards we are dealt.