What's The Right Way to Do This?

I'm just now starting to use git for more than trivial things. Today I got myself in trouble. Here's what happened:

1) I pulled the master branch from the IT repository from our
main git server.

2) I created a branch from this called "J" and started making changes.

3) Other people pulled master from IT and then pushed changes back.

4) I merged J with my master branch.

5) I tried pushing my master back to origin but this failed with
the usual message saying I first needed to pull from origin.
So, I pulled and then pushed. This worked.

6) On another server where I was going to use my changes I pulled
master from IT.

6) It turned out that my changes were incorrect. So, I tried to revert
using various methods I found by googling "git revert". What happened
was that when I tried to revert back to the commit before the one I
made, the files I had modified *and* the files that apparently were
modified by other people in #3 above were reverted. This wasn't what
I wanted. I only wanted to revert the changes I had made.

With the help of someone more experienced than me we were able to get things back to normal but this experience left me wondering what I should have done in the first place. There's a chance I'm going to have to go through all this again as I try to fix the problem with my changes.

Any suggestions would be appreciated.

Thanks, Jon Forrest