Well first id say that practice is key. But another factor that is probably the most important is that you have to find the right height for YOU. Yeah Slash looks cool as hell playing his guitar that low but that works for him. and while i understand that playing your guitar very high doesnt look fabulous, all you need to do is just find the height were your comfortable, then if you want it lower, you can try lowering it progressively as long as you dont sacrifice playabilty. Then do it until you find your spot or, sadly like it was with me, until you just cant play well anymore!