I started playing poker in March with the free 75$ from PSO and turned it into 7500$, playing only NL ring games.. so I think that I might help you.
I'll give you my progress by month and at which stakes I was playing
March: 500$ NL25
April: 975$ NL25
May: 350$ NL25 (I had a very bad streak)
June: 925$ NL50
July: 500$ NL50 (didn't play much)
August: 1300$ NL100
September: 2000$ NL100
October: 1100$ NL100 and some NL200 (not playing much)
As you can see, I was taking my time before
moving up.
From my experience, NL25 is not different from NL100. If you have let's say a 4BB/100
winrate at NL25, you should be
able to maintain the same BB/100 at NL100 without
adjusting your play. You'll have plenty of players calling with mediocre hands or draws. You can play
ABC poker and win easily. This statement does not hold between NL100 and NL200 (but you're not there yet

The
level between NL25 and NL100 is exactly the same, but it may seem different to you if you start playing scared.
Moving up is a good thing as long as you keep playing your game, even if you have more money at the table. Do you mind losing 50$ or 100$ in just 1 hand?? If yes, stick to NL25. I wouldnt mind losing 200$ on a hand, but I would be pissed to lose 1000$ (so that's why I'
m not playing NL1000!)
One advice that I'd give you if you think you might be ready for NL50, is to play 1 table of NL50 and 2-3 tables of NL25 at first (I assume that you're already multitabling... otherwise ignore this). Each time I move up, I do it gradually and it has worked very
well for me.
Finally, if I had to start over again knowing what I know now, I'd move up a little bit faster because I know that NL100 is not a different game and this is much more profitable for me.
I hope it helps!