I would recommend one of the most important things is not using magazines.
A golf swing problem is like an illness: you have to find the right cure. You can't take someone else's medication in order to fix it.
Furthermore, it depends on your skill level. If you're a beginner, take 2-3 lessons with the local pro to ingrain the basics.
If you're a little more advanced, and don't want to spend money, then there are many self help drills.
I have a hub on the subject: https://hubpages.com/sports/My-5-favorite-Golf-Dri