Again, my number one tip involves a bag.

Keep a diaper bag stocked at all times. Buy duplicates of products to stay in the bag. There is nothing worse than realizing you left the butt paste (Dr. B's Butt Paste is AWESOME for diaper rash) at home.

Pack a thermometer and fever medicines. My oldest son Sam had fever siezures when he was little. They were scary so we always had fever meds on hand. Generally, you can give Tylenol and Motrin every 6 hours but if things are bad, you can alternate them and give one every 3 hours (See you doctor for real medicial advice =)

Remember to pack an extra outfit and blanket for "down below" emergencies. I'd also recommend a small kitchen towel for messes.

Carry plastic bags for those messy diapers. You don't want to be there person who stunk up the bathroom so you can confine the nastiness in a plastic bag and then throw it away! It also helps confine clothes that have been soiled for the trip home. You can get baggies prepackaged (I had cute blue ones with a duck dispenser) or just recycle the Wal-Mart bags (what I did when I ran out of the cute duckie ones)