Well, advice is free and plentiful here.... so 100 people could give you 100 different answers... but here's my opinion...
1. Use the hell out of what you have. What every your doing know, whatever your using now, keep doing that until your skills, and ears outgrow it.
2. You'll need a pretty good computer to record and mix 16, 24, 32 tracks, and considering reverb plug-ins, delays. etc.
3. You need an 'audio interface' to get into your computer via USB, Firewire, or PCI card. These are getting better and better, and coming down in price all the time. I highly suggest this:
http://www.m-audio.com/products/en_us/ProFire2626.html
or
http://www.m-audio.com/products/en_us/FastTrackUltra8R.html .
4. You'll need a DAW software. Reaper is great, but so are many others. (Cubase, Sonar, Ableton).
5. Once you've got your Audio Interface installed on your computer, and talking nicely with your DAW software, you'll want some plug-ins. Reaper, and most DAW's come with their own, but you'll want to get a handful of others as well. There are many FREE plug-in's available.
http://www.sadglad.com/freevstplugins6.html
Some of the free ones are very useable, and some are not so good.
6. Personally, I think it would not hurt to have a subscription to EQ magazine, or Sound on Sound. There is alot of great info on this forum, and on gearslutz.com. Do alot of reading, and you'll soon realize who the big dogs are in those forums. You could end up meeting some very high profile industry people. (There are some celebs in this forum).
7. I forgot to mention, and should have mentioned earlier on... your room and monitoring. This is important, but too broad of subject to explain here. Anyway, you'll want to make sure your not having reflection issues, standing wave issues, etc. in the room you are recording and/or mixing in. You'll also want some nice neutral monitors, which don't have to cost you a fortune. Some AKG K240 headphones are also good in a pinch, if you want to mix and take the room out of the equation.
Many people here will tell you that your room is the most important thing. I don't know alot about the subject, but I've got baffels (office dividers) in key places, and as well, I bought 2 bales of Roxul, and made myself some cheap and easy 'traps'. When I clap my hands, I get no echo, and I've done some testing with an analyzer, and I seem to get a pretty even picture across the freq. spectrum. Seek out Ethan Winer on this forum, he is the master. Also visit
www.realtraps.com.
8. After your 'in the box' - stay IN THE BOX. Everytime your system does an A to D or D to A (Analog to Digital) you could be losing something, or adding a distortion or delay, so... once you've recorded something, leave it in the box.
Having said that, it makes it pretty easy to know what to invest in from there... GREAT Microphones and GREAT preamps.
IMHO... don't mess around with singal/dual channel $300 pre's. Wait until you've got $1000 to $2000 and then do it right. I've bought too many cheap pre's, and have been disappointed. As soon as you buy one of the serious pre's.... API, NEVE, Daking, Universal Audio, etc. you will hear it. There will be a big difference.
Until that time, you can get buy on the OCTANE pre's that are in the 2 devices listed above.
I've spent more than $5000+ on crap I didn't need, or crap that didn't pan out. I am finally happy with my setup, and I am now getting good results. Some of the stuff I have recorded has no been on the raido, and the bands I am recording are happy. So... Hope some of this helps you out and saves you some money.
There are a whole lot of people in this forum with a heap of experience, so READ READ READ !!