How do you get good a drawing?

Quite honestly drawing should be a fun thing, so try practicing the kind of thing you like. If you want to get good at drawing in general I would suggest practicing from still life. Other good starting points are taking pictures and if that is a challenge try making a proportionate grid on the picture and the drawing paper to help make an accurate copy. I consider myself above average in drawing skill but I got there after about 10 years of practice (if you really try and stay consistent, your skill will gradually improve). That's pretty much all the advice I can give in writing, but other options are to observe other good artists you know; use them as a benchmark of sorts.