There are few constructed trails here, but in a place this desolate you usually don't need them. Most hiking routes in the park are cross-country, up canyons, or along ridges.
The best time to hike in Death Valley is from November through March. Summer temperatures can be dangerous in the park's lower elevations. Even during spring and autumn the heat can be unbearable for most people. Save the low elevation hikes for the cooler winter days. The high peaks are a pleasant escape from the heat in summer, but are usually covered with snow in the winter and spring. If you must climb them during winter season, be sure to be properly equipped with adequate winter clothing, an ice axe and crampons.
Due to the dry climate of Death Valley, you must drink more water here than in other places, even in the cooler winter months. Always carry adequate water (at least 2 liters for a short winter dayhike, 1 gallon or more for longer warm season hikes and overnighters). Springs are rare and should not be considered reliable. Boil or treat water from these sources before using.