* Are you using gitk viewer?. Specifically "gitk --all". Open it, leave it open, and refresh it after running any Git command to see what you did. Stick with gitk too, don't be tempted to reach for a viewer in your favourite toolkit/webapp implementation just yet. A long time ago, too many GUI were either focused on single branch, or did not render the whole branching/merging adequately. I'm sure that's changed, but gitk is part of git, and experience with it will mean you're in a position to evaluate alternatives later.
* Erase all knowledge of "git pull" from your brain. Basically a "fetch+merge" in one step, it's like leaving a parked car in gear, but with more mess when you get it wrong. Replace it with "git fetch", followed by inspecting in gitk, and deciding if a "git merge" is what you want.
With both of these I found developers were often more developed in their understanding than they thought they were; they just needed a 'leg up'. With these their confidence and understanding improved dramatically.