In order to select a first aid kit, you must take into account under what circumstances it is likely to be used. Think of the convenience of the packaging, where you will keep it and consider all the needs of each member of your family.
Your home should be the first place to have a kit for most home injuries can be taken care of quite easily. When children are involved you know that most accidents occur in the home and in the kitchen. A good burn kit should be included, as well as instructions for what to do when someone is choking, has ingested poison, or has an eye injury.
In everyday travel from home to work, or school you should have a kit. It can be something small in a purse. Every parent knows when taking kids to the park anything can happen from a small scrape to something more severe like a fracture. Usually all that is necessary is a kit that has bandages, of course, some antibacterial ointment, and cleansing wipes. This you can create yourself or purchase ready made for those accidents that didn't occur to you.
When going on a camping trip something more extensive is necessary and a large box may be inconvenient to carry when are backpacking. There are kits available that are waterproof and in bags instead of the metal box. This kit should not be self made but bought for all possible emergencies for the area you may be camping or backpacking. If you have anything you must have such as prescription medicines just add it to the kit.
If your family has special needs be sure to purchase your kit to fit those needs. Or you can purchase a kit and add what is necessary for your circumstances to remain safe. If you have someone with you that has a heart condition you may need to include a defibrillator.
All kits should have some instructions on what to do in case of emergency. The more expensive kits even include audio instructions to walk you through what to do. This may be a better option when panic is starting. Prepare yourself by reading the instructions and possibly taking a basic class to walk you through different kinds of emergencies.
First aid kits come in all different sizes and with different tools in each. When you choose make sure it is best for you, consider price and if necessary create your own. Use brand name materials when you can and be sure to check for expiration dates. Keep your kit supplied and updated so you are never caught in an emergency without any way to help yourself or your loved one.