Yosemite National Park is home to many tall mountains, trails are often loose, steep and dangerous (with little or no room for error).
Wear broken-in, sturdy shoes that have good traction.
A note of caution: Because many of the Yosemite's hikes have steep ascents and descents, often your heels and toes will get particularly pressed. Make sure your shoes fit properly and that you bring along some blister care and other first aid while hiking.
Pay attention to your breathing when hiking in Yosemite.
When you huff and puff your body is not getting enough oxygen. Walking at a pace that allows you to be able to walk and talk means that your legs and your body are getting the oxygen needed to function efficiently. (IF YOU CAN TALK WHILE YOU ARE WALKING, YOU ARE WALKING THE PERFECT SPEED.) When your body generates fewer metabolic waste products, you enjoy your hike more and you feel better at the end. At times it may seem like you are walking too slow, but at an aerobic pace (sometimes even baby-sized steps when the trail is steep) your energy reserves will last longer. You will also feel much better that night and the next day.
Take a break at least every hour.
A break of ten minutes helps remove the metabolic waste products that build up in your legs while hiking. Take a break at least every hour. Sit down and prop your legs up. Eat some food, drink some fluids, and take this time to enjoy and appreciate the view. These efficient breaks can recharge your batteries. In the long run, breaks will not slow you down.
What goes up must come down.
Many visitors and outdoors enthusiasts can't wait to explore Yosemite's high country, including Half Dome and other tall rock walls and mountains. Just remember the summit, or the turnaround point, is only the halfway mark. You still need to get yourself down, and back to the trailhead safely. Only embark on hikes that are commensurate with your physical condition and fitness level.
How to navigate if you are lost:
Step 1: Adjust for declination
Declination is simply the difference between magnetic north (where the compass needle points) and true north (the North Pole, and the direction maps are oriented). To navigate accurately, just check the margin of your map for the declination (12 degrees east, for instance) and adjust your compass accordingly (most have a simple dial). No dial? No problem. If the declination is east, subtract the degrees from the magnetic north bearing to get the true bearing; if it's west, add the degrees (easy mnemonic device: East is least, west is best).
Orient your map
Lay the straight edge of your compass on the map so that its true north bearing is parallel to the map's true north grid lines. Rotate the map and compass together until the compass points due north. Video: How to Align Your Compass with Your Map
Step 3: Take a bearing
Let's say your destination is a spectacular lakeside campsite two miles off the beaten path. You can see it on your map–but not from the trail. To get there, lay the straight edge of your compass base plate on the map so it connects your present location with the lake. Turn the compass housing until its meridian lines match the north-south lines on the map (make sure the arrow is pointing to the top of the map, or you'll be 180 degrees off). The direction indicated at the compass's direction of travel arrow is the route you need to take to reach the lake.
Step 4: Navigate around obstacles
In the real world, obstacles like canyons and cliffs can get in the way of your straight line bearing. Here's how to go around without getting off track: With your compass in hand, sight an object–like a tree or boulder–that is beyond the obstacle and lies on the straight line to your destination. Hike to that object by the easiest route, then resume traveling along your original bearing.