I tried making a level several times in August-September last year, but for each try came a point where my editor save file was so bugged ridden that I had to start over, and lost many hours of editing.

So I was reduced to just thinking of ideas for my mod and lurking in the forum.
Now I got this feeling, by reading through people's threads, that the editor is in a workable condition, though still with some flaws. So I've decided to give it another try!

Now my questions are as follows:
How can I make multiple save files, so I can have older versions and therefor backtrack?

And more important, what bugs or errors should I look out for and are there any precautions I should take before starting on a new level/mod?