I would add to the list of posters who have recommended taking a first aid course...Good Samaritan laws are slightly different from state to state, but across the board it seems that the best legal protection you can have is to have a certification from some agency stating that you have been trained and evaluated, and then doing just what you've been trained to do. There are several companies that teach a lot of wilderness-oriented courses; I would say that the top three would be Wilderness Medical Associates, Wilderness Medical Institute (owned by NOLS), and SOLO. There are also some more regional bodies, such as WEMSI in PA. For people who work in the healthcare industry already, the Wilderness Medical Society is not to be discounted, though they seem to offer more research activity as well as a fellowship option.(Disclaimer...I teach for WMA, but have met people certified from all of the above groups and have found more similarities than diferences)

All the talk of tourniquets is interesting, so I thought I'd comment...tourniquets are also posed to make a comeback in frontcountry EMS, particularly for SWAT medics. Recent studies have indicated that tourniquets can be applied for up to 4-6 hours without lasting tissue death. Since the normal clotting process (without other factors such as hypothermia or certain medications) is around 15-20 minutes, there seems to be a good strategy to applying a tourniquet initially to control life-threatening bleeding, then slowly releasing pressure after about an hour. I would also (not had the occasion to do so), use a tourniquet to temporarily stop blood flow while cleaning a wound if I anticipated moderate to severe bleeding. Realistically, though, well-aimed direct pressure and elevation will stop about 95% of bleeding in the civilian world. Tourniquets are popular with military medics, IMO, because they routinely encounter multiple patients while people are shooting at them.

In any case...my personal kit contains mostly "routine maintenance" items like blister care, band-aids, both ibuprofen and tylenol, an anti-diarrheal, some trauma supplies like triangular bandages, roller gauze, and vet wrap, and some wound cleaning supplies. I packed it this way based on my prior experiences with what I typically encounter (and that's an important distinction). The biggest advice I can give is to leave the McGuyver suture kit at home (including butterfly bandages)...the types of wounds that truly need suturing require training and experience, and closing a wound leaves it prone to infection.

A particularly good (IMO) reference is "The Outward Bound Wilderness First-Aid Book" by Jeff Isaacs. Not particularly pack-friendly by UL standards, but a great reference to be used in conjunction with wilderness first aid training.

Hope that helps, PM if I can be of further help!