I always think a book (manual or similar) is the best bet for getting the fundamentals down and then using websites like Ken Stones or Creative Cow or ours at Pro Juice TV to get hints, tips and tricks to move your work further.
Pro Juice TV
http://www.projuice.org
Music Video Multimedia
Pro Juice is a weekly presenter driven online portal and television series about music, video and multimedia for guerrilla producers that want to make, distribute and market their media
