Best way to master regular expressions is to use them in your day to day work.
Use a regex aware editor. I recommend NotePad++. Use the find and replace functionality with regex enabled.
You need to know just the basics to start off. Words, characters, numbers, white spaces.
They are quite easy to remember. You don't get everything right the first time. But you will learn every time you try it.
Remember, unless you use it regularly, you will probably forget regex in couple of weeks.
