Can you realistically raise your ACT after taking it several times? I only have 2 more opportunities and have hit a brick wall in terms of raising my score.
Study the fundamentals, dude. The ACT is all about what you know!
Get "Getting into the ACT" (the official stuff) and practice as much as you can. I would also try "Cracking the ACT" (from PR, which IMHO is the next best thing after official stuff)) for general strategies and for more practice tests. I have the 2005 book (I think 2006 is out now, not sure, don't need it! lol) and it is really solid.
What are you scoring now? What are you trying to get to?
What really helped me was to get study guide software that had puzzles and games on it. I would get comfortable, listen to music, and do ACT study-games every evening after school. I basically did this instead of watching TV. The games kept my interest whereas a regular study guide was horribly boring. I raised my score from 29 to 33 doing this. I wish I could tell you what software I had, but it's been too many years (it was on a 3.5" floppy!)
I used the same strategy for the GRE and I saw a major improvement in my vocabulary score within days.