Replacing the headlights in your car is not a complicated matter, and it doesn't take you being a professional to handle it. When performing H4 headlight LED replacement, you should, however, contact a professional about what lights you should get and what fits with your type of car, and also if your car has any certain protocol when it comes to switching the lights; some cars need to be partly dissembled for you to be able to switch the lights. The most important thing to think about when switching headlights is that you stay safe doing it and that you don't harm the bulbs.
Don't use your hands
One of the most important things to remember when changing headlights on your car is that you don't look directly into the lights when testing them. LED lights are safer than many other types of lights, as they don't create any heat that you can burn yourself on, but the light itself can be damaging for your eyes. Always wear gloves when performing H4 headlight LED replacements regardless. They should be flexible enough to handle the procedure of replacing the delicate bulbs but thick enough to keep you from getting injured if the bulb were to burst.
Grease it up
To make your light bulbs last as long as possible, you should use grease specially designed for headlights, and prepare the bulbs with that before replacing the bulb. This will keep dirt and moisture out of the light fixtures, which will be able to increase the life length of the bulbs themselves. It also works as an electrical contact, which means your bulbs will shine brighter for longer. You should make sure to apply a new round of grease on them every now and then to make sure they fully benefit from that advantage.
If you're switching headlights due to an accident or other violence that has caused your headlights to break, then you should make sure to realign them after replacing the bulbs. Simply put your car in front of a garage door, or other flat surface, at dusk or in the evening. Look where the light is pointing on the flat surface and make sure it's pointing straight out of the headlights. If they are a little bit crooked, you shouldn't try to just fix them yourself by turning the light bulb. Even if they're just off by a little bit, you can still damage the vehicle by handling it improperly. If they're crooked, then you might have to call a professional to get them realigned.