So, you made the choice to become a magical girl, huh? This is a big decision to make, but you've probably heard that from me a dozen times already. Now what's important is that you know what you're doing. The actual methods you'll be using to gain your abilities are fairly easy, and you may or may not know how to use them already. In fact, finding your destiny as a magical girl can be very easy if you know what you're doing!
First, you need to do something called an F-Shift. an F-Shift is easy, you just decide on who you'll be as a magical girl. Go into as much detail as possible here, as that'll make every other step easier. When you do your F-Shift, try to get at least these things set in stone:
The series you're from
Outfit
Powers
Title (if applicable)
Transformation item
Mascot (if applicable)
These are only a few things, and you would probably benefit from even more, but that's a conversation for the F-Shift page. Next up is the script, which is definitely harder, but mostly because there are so many ways to go about it. You essentially just write down everything you want as a magical girl, down to every little detail. You can write it over and over, or pretend it's already happened, it really depends on what works best for you.
After you've finished that, the really exciting things start to happen. You need subliminals to get here, and it's either here or in the last step where any previous experience starts to get useful. The M-Shift is where your mind starts to lean toward being a magical girl. It's important because you need to really be in the mindset of being a good person, of helping people and such. It's the only way you can become a magical girl.
You've finished all of that, now what? By now, you should be seeing some results, things like higher stamina, better luck, signs from the world; it could be anything. Now you just need that final push to make you transform. This is where you should start expecting any transformation scenarios you scripted to start happening, or if you don't have a mascot to make you a magical girl; this is where you should start practicing your abilities. They'll come soon, you just need to practice just like anyone else would!
And congrats, you're now a fully fledged magical girl! This is generally what you should expect on your journey, and this site should tell you most of what you need to know (if everything goes right on my end!) Please see the little next button down there for your first real step on to your adventure.