I foolishly tried full series fandubs for both Sailor Moon and Tokyo Mew Mew (remember that show?) back in early high school, but never got past one episode for TMM (and nothing for SM). Even with a partner doing the mixing and helping with the writing, it was still too much work. There's also actors and scripts to keep up with. Projects like that are almost guaranteed to have actors drop out or not respond, so be prepared to recast. If you're in school, forget about it. Goodbye freetime, and probably your grades too. In hindsight, I do not know what I was thinking and am thankful both projects died early.
Once upon a time, I was go-to amateur voice actor for guy roles in magical girl anime fandubs (also including ones I didn't care for like Mermaid Melody and Shugo Chara). I voiced Mamoru/Tuxedo Mask many times, Jadeite at least once, and pretty much every major guy in TMM (especially Ryou). Just doing voices for fandubs isn't nearly as time-consuming, but at it can eventually lead to professional work in indie games, etc. Lots of young voice actors for anime and video games got their starts in fandub-type projects.
I was a voice actor in a longrunning fandub of the DS game Magical Starsign that actually completed the thing (I was a regular voice for bit roles). It took years, with the girl in charge even taking a few months off to have a baby, but she still finished it. There were only two major recasts too (one of which did go through four actors though). It was a bit easier though since she was just adding voices to text bubbles. That was back in the good old days of Voice Acting Alliance.