Typically in economy, you can bring one carry-on and one personal item. If you bring two bags, one must fit underneath your seat and the other can go into the overhead bin. If you're flying in an upgraded class like business or first, you may be allowed an additional carry-on bag.
Do my toiletries have to be in a clear bag?
It's called the 3-1-1 liquids rule. Each item must be 3.4 ounces or less and must be able to fit inside a one-quart size clear zip-top bag. The limit is one bag per person. Typically, travelers put their toiletries in the bag such as shampoo, hair products, make-up and toothpaste.