How do you guys fly well in the game?

I will say that I'm a new player and I play on PC. Everytime I managed to get airborne it all goes down hill from there because I'll use the WASD keys and anytime I hold any key for longer than a second, the plane acts like I held it for 10 seconds and it makes a massive turn to whatever side I was trying to go and then trying to correct it becomes a nightmare. I just wanna click the keys and expect the plane to slowly turn or elevate/decend, not try to do a whole barrel roll and end up getting out of control beyond recovering. Anyone got any ideas?