The best advice one can receive. If you are really serious about improving your work then you must realize that improvement & changes will not happen overnight. Watch video tutorials, get books on anatomy, perspective, learn to draw more than just people as well...watch videos on coloring and try to improve at that as well.
But most of all...just draw. Don't put pressure on yourself to "improve by XXX deadline"; just draw because you want to get better. No timetables...