You may find that, even after tweaking the limiter a bit, you’re just not able to get acceptable sound quality with the level of loudness you’re going for. That’s understandable – music these days is mastered incredibly loud. It takes a lot of skill to get stuff that loud with good sound quality. (There’s also a lot of stuff out there that’s really loud and sounds pretty lousy as a result.)
In many cases, the best next step is to settle for less volume. Just back off a few dB and leave it at that. Unless you’ve got some solid skills and good tools, you’re probably only mastering things to play for other people, put on Soundcloud etc. It’s OK to be a little quieter than the next guy. Anyone who’s opinion you’re really interested in would much rather hear something a little quieter than something horribly squashed and distorted.
Not much of a tip you say? Perhaps. What I’ve been getting at with these previous tips, though is that even with very limited tools and experience you can help yourself enormously by doing some careful listening – and avoid making the common mistake of over-limiting your music!