Make sure to land your 180s exactly where you need to, if you're consistently landing off-balance to one side or not rotating the right amount, work on fixing that before worrying about fakies. Once you get that, keep in mind that fakies require much smaller and more precise adjustments to maintain balance than normal riding. The main mistake I see people making is steering entirely with their arms in fakie, and over-correcting too much to ever settle into a nice casual fakie. Steer less with your arms and more with your knees and butt, and make smaller corrections than you think you need to.