First up the Korean name for taekwondo front kick is Ap Chagi.
Your target should be straight in front of you.
First lift your knee towards the target. Then drive your foot out towards the target by straightening your knee.
Then bend your knee to bring your foot back. Before placing your foot to the ground.
Just so you're clear...
Your knee bends. Then straightens. And then bends again.
Got that? Here's more detail
Your foot position is very important for an effective tkd frontkick. You're aiming to strike through the target with the ball of your foot.
To get this right try pointing your toes like a ballerina. Then pull your toes back while leaving your ankle in the same position. So your foot is extended but your toes are back.
It might take you a while to build up the strength in your foot to do this. You can try practicing while you watch TV.
Try to achieve this foot position as early as possible in the kick. Ideally by the time your knee is chambered your foot is in the right position.
To get more power in the kick you need to use your hips. Your taekwondo front kick should penetrate forwards into the target. And to do this with power you need to drive your hip forwards into the kick.
But not so much that you end up leaning backwards.
Your standing foot needs to rotate. This helps you to use your hip properly. As your kicking leg comes through allow your standing foot to naturally turn outwards about 45 degrees.
Keep your knee up through the kick. It's important that your knee doesn't drop down until your foot has come back.
As always...
Posture and core strength are important. Try if you can to keep your body upright. And allow the kick to happen independently of your body. It's great if you can keep your abs tight and your shoulders relaxed.
And if you're struggling? Try building strength by doing slow frontkicks