How to practice effectively

I live in an area without any instructors. I much prefer noter drone style playing. I am participating in a slow jam group geared to beginners but most in the group are at least 7 months ahead of me in the group and are therefore much more skilled as beginners.

I need to know how to practice. I think I  am making mistakes and continuing to practice those mistakes because I don't recognize them or don't know how to correct those mistakes. Have tried DVD's and other media without success.

Any points or pearls of wisdom greatly appreciated.

Thanks for any responses.