Cows are notoriously quite ninja for the untrained.
More seriously (and more importantly), with regards to healing, you've got two methods: First is gauze, which is made from wool at a loom (I imagine it requires First Aid.) The loom requires clothesmaking, I believe. It restores 10 HHP over time, or so I've heard. Some people claim it restores HHP indefinitely. To use it, click on the gauze in inventory, and drag it to someone's character sprite and right-click. Use the only option, Treat Head, and they'll be bandaged. Keep in mind this requires that you don't have any headgear on at the time, as the bandage is effectively a hat.
The other option are leeches, in swamps, which will do SHP damage (the first number on your HP bar) but have a chance to heal HHP (the second number on your HP bar). You'll get them randomly 'equipped' to your empty equipment slots in swamps.
As for combat, you'll need to invest a few LP into unarmed to kill a cow, most likely. You can also use
combat moves, or instance attacks, to give you a higher chance to hit. The easiest one to do would be Strange, which requires you to have nothing equipped in your hands and can be used with the hotkey K->G.