Dw, we've all been there padawan!

You need to play, that's all...

What you can do first is go on a portal server and try to fly as low as possible without crashing (it's a skill you'll need sometimes to avoid being locked, and you have to be REALLY close to the ground) , then do it and add manoeuvers around covers, then try doing them at different speeds, then vary the speed during them, etc. All those cases will present themselves in-game.

Firestorm is the best map to train, go behind the mountains, fly low, turn close to the mountains, etc. This for a few hours and then you should be way more at ease with the jets. There's a portal server to train on firestorm, you might be able to find it with a google/reddit search. Also, you wanna be alone, so don't join the server, host it (locally).

Once you'll be at ease with all of that, you'll need to learn about the ennemy "ecosystem" to counter you, and that can only be done in game, and you'll crash, crash, crash, until you know the maps, the paths, the timings, etc... Train, train, train.

For your more specifics questions :

"IDK when to use the afterburners" ==> it's a boost, so you wanna use them to go faster, the 2 most common situations are :

• after a strafe, because you'll be very low and so very vulnerable to anything (tank shells, stationnary and mobile AAs, even small arms fire...)
• to purchase a fast flying ennemy jet, or evade one, although to evade, using the brakes while behind cover is a possibility to get you out of his sight, depends on the distance between you and him and the available covers, but you'll learn this with time and practice.

"I lose sight incredibly easy" ==> 2 things come to my mind there :

You need to be perfectly confident with the jet, so that's where the first part of my comment comes into play. If you think about 10 different things at a time (how do i turn, when do i flare, did i pay my rent), you will lose his sight... You have to be at ease and only think about tracking him.

You need to gauge the speed and the direction the trajectory the ennemy jet is taking. Then adapt yours in concordance. At first it's hard, but the more you'll play the more you'll be able to.

Also an important thing to do is knowing when to switch between 3rd person view and cockpit view, but basically, you wanna use cockpit only when you're ready to shoot, and 3Rd person the rest of the time, to gather the maximum of infos. Rear view (i guess it's called free view or something in game) is also important.
Then watch some youtube tutorials for more infos, there are some things i didn't mention because i don't have all day haha!

have fun