I only got back into modeling about 2 years ago and I have to say having the means to buy the various nice to have tools, air brush, compressor, etc along with the higher quality kits and model building books / magazines has helped my modeling ability more than just the age difference would suggest, even though I have most all the tools I would like, I have found that I probably rely on an $8 pair of sprue cutters, a $3 razor knife (like a little carpet cutter), sanding sticks and paint brushes for 80-90% of my modeling.
I also agree with the imagination comment, not just for building but for making tools, when I started scratchbuilding I saw a $60 cutting table for cutting styrene, I went to Home depot, bought a small piece of laminated wood, and a couple of squares, I made a table I think is better than the commercial one and I did it for about $15.
Money is important but I wouldn't say it is most important, now I would rate the internet very close to the top, I have learned so much just by coming to sites like this and asking "how do I...." it is amazing how helpful having hundreds of modelers available is particularly when you consider there is usually a lag of less than 24 hours before some good info has been provided.