Not counting that failed startup i was a part of (which got big, but it doesn't count because a team worked on it, and you asked for 90% 'your own'), i'd say Phynd 4, including the home site. It also has a little bit of C (for an external helper program, not embedded), but id say its 95% in perl.
- Vanilla Coke. By the bucket. Diet counts too.
- Modularize where you can. (Althoug this was mostly appropriate due to the project.)
- DBI is your friend.
- Keep things neat and organized! I can't tell you how much of a difference that made (both good and bad when done/not done, respectivly). subs and "comment blocked" code, so that its easy to come back to a section after working on an entirly different part of the code for long periods of time. As your project gets large, this will occur more frequently and thus becomes more important.
Probably the biggest mistake i made was trying to do everything in one shot. Working on a project alone, every time i would complete 1 task, i would htink of 3 others that would be great to have. The end result was a .0 release that, in all honesty, should've been a .9 release. As of right now, i'm working on a .1 release which is what i imagined the .0 release should've been.
If i had a technical document, i would've been much better off and had much clearer goals. I would reccomend one.