Grab 2 dumbbells that you feel comfortable with lifting. It's best to start with lower weights and increase as necessary to prevent injury.
Move to a bench, preferably with back support. Keeping your back straight while performing this exercise is essential and greatly reduces the risk of injury to your back.
With the dumbbells at your feet, grab one in each hand and lift them up to rest them on your thighs.
Use your legs to help push the dumbbells up as you lift them to roughly your shoulders height while rotating your wrists so that your palms are sticking straight out. This is the starting position.
Using your shoulders, exhale and push the dumbbells up until your arms are nearly straight. Avoid locking your elbows when you reach the top.
Inhale as you bring the dumbbells back to the starting position. This completes one rep.
Continue for the necessary number of reps. On the last rep, move the dumbbells from the starting position back to your thighs. You can let them rest there between sets, or place them on the ground.
Additional Information: This exercise mainly targets the deltoid muscles, but also engages the triceps as well.
As with most free weight exercises, it is a good idea to use a spotter. The spotter should stand behind you and keep their hands a few inches below your triceps as you push up and on the way down.