A. I would not have delved into marketing online/internet marketing products and services as a newb. As Lisa also stated I would have targeted a niche I was passionate about and would have devoted more time to....which would probably have led to developing an info product around that niche.
B. I would not have shelled out $$$$ on regurgitated eBooks by "gurus" when all the information you need is readily accessible on the web if you know where to look.
C. I would not have focused on ONE "golden egg" site for years. I think many marketers get wrapped up in one site too much instead of
building their business. In the beginning I think I saw affiliate marketing more as a hobby. If you're going to get into this you need to look at it from a business perspective
from the start and sit down and formulate a business plan on how you will
make it grow.
D. I would have outsourced much of the work I did myself (i.e. scripting, articles, copywriting, graphic design, etc.) via
www.elance.com and
www.rentacoder.com from the start.
You can't do everything yourself...that's why people have jobs 
If you do everything yourself you will never really do
ONE thing exceptionally well. In addition, it will take you longer to bring your new products or services to market which can severly affect your initial ROI.
Umm...I'll probably add more to this but that's just off the top of my head.
