I'm playing almost all the time 9 handed 0.1-0.25, i tend to play really tight,i see the flop in 18-25% of the time. Is this number ok for that limit and should i play more pots in the higher limits?

Are you playing pot limit or fixed limit? If it was fixed limit, I would reccomend playing more pots and building up pots when you have solid equity in the hand.

If it's pot limit, I would reccomend staying near the 25% threshold, and focusing mainly on playing pots in good position, which will make a huge difference in your profitability in the long term.

also check this out for some basic advice.

It's no limit, the most painful variety 

no limit, it almost doesn't matter. there are winners who play 10% of hands and winners who play 35%. they can both win the same. pot limit is pretty much the same deal.

That surprises me a bit, is it the same at the higher limits? I'm wondering because the next level seems tough for me because of my tight play, i don't feel comfortable at 0.25-0.5 although its not a big step forward. I have the feeling that i lose much more money because of my tight play, is it just a psychic thing?

one of the biggest winners at .50/1 plo8 played like 10/2/3. the guy who is actually the biggest winner plays around 27/14/1.5.

how you play preflop sets you up for how you play postflop, but this game is really won and lost on the later streets.

Those percentages dont make you a tight player. Those are good numbers for a solid middle of the road strategy.

Yeah i feel it's ok for this limit but somehow i've got the feeling that it doesn't work that well  at .25-.50 anymore. What do you mean by "middle of the road strategy"

not too tight and not too loose.

those are my numbers and i do alright at that limit.

o8, especially pl and nl, is a game where vastly different strategies can all be fairly equally successful, but it depends a lot on your skill postflop. as with most games, the more skilled you are at extracting value/bluffs, and bluffing yourself, the more hands you can play profitably. if you're not comfortable really doing those things, then you should play much tighter.

that said, i don't think that you can really play like 50%+ of hands profitably, but anything up to that at almost all games should be pretty ok, depending on what you do postflop. fwiw, when i play plo8 tourneys, i play literally every hand that's not 3bet preflop for the first couple levels.