I'm currently on my 4th foster litter, in 2 years. I wish I would have known sooner that it is a good idea to get a little kitchen scale to weigh each kitten daily, so you can be sure they are all gaining steadily.
Read the "stickies" at the top of this board, and it will give a link to what items to have on hand. A good thing to have is your cell phone, with the foster contact person's name, and the vets #! Then when you feel panicky for no reason, you have someone to call. And someone else in case something really goes wrong!!! LOL!