Grab parallel bars; hold your body at arm’s length (arms locked) above the bars. Your torso should be leaning forward at around 45 degrees, with your knees bent.
Lower yourself by flexing the elbows. Your elbows are directly above your wrists. As you go down, bend your knees to a 90 degree angle. Keep your torso straight and aligned with your thighs in a diagonal axis all the way through. Use your chest and triceps (eccentric contraction) to bring your body back. Breathe in as you go up and breathe out as you go down.
As you go down, let your chest overtake your wrists. Make sure your hands are in the correct position and avoid extensive dorsal flexion in your wrists. As you go down, avoid lifting your shoulders and eliminate using your upper trapezius muscles. Keep your torso straight and aligned with your thighs. Focus on abdominal breathing!
It is advised to use a spotter to hold your legs near your feet.
Dips are an excellent exercise: compound, basic, developing multiple muscle groups and relatively safe. However, they can also damage the shoulder joints and people susceptible to joint injuries will usually have to avoid doing any form of dips.
Dips have two other disadvantages: you can’t do them if you didn’t achieve certain level of strength and you cannot easily fine-tune the weight (resistance).
The first problem can be solved by leaning with your feet on a platform (bench or other) when doing dips, the second one by using dip belt.
Dip belt is a belt with attached chain for weight plates.
To emphasize your chest, do the dips with your torso angled forwards. Upright dips are mostly strengthening triceps muscles.
The most common version of dips is with the bent legs. There is another, more demanding version called Gironda dips (after the famous bodybuilder Vince Gironda) with legs stretched forwards. There are athletes that swear by Gironda dips so you may give them a try.