It probably really doesn't have to be pointed out...but THIS IS RATTLESNAKE COUNTRY. As you walk through these trails, admiring the scenery and sites, be aware of the fact that snakes are present in the area.
Always stay on the trail...that's your best safety, but remember snakes don't read signs...
If you're visiting any of the ruins, remember the environment you are in.
The summers get very hot..remember to bring plenty of water with you. Most of the sites in Hovenweep and the Canyons of the Ancients requires a distance of walking.
Be prepared. We like our "CamelBack" backpacks, which put the water on your back, accessible easily by a drinking hose attached at your shoulder.