+1 your econobox won't compete with the "performance cars". Your wagon is awesome though and I am super jealous of it. You can add some really sweet mods to it too. Keep an eye out for any factory optionals your car is missing, though most DX wagons are usually pretty well equipped.
The factory rims on her are the OEM factory alloys for the 7th gens, but they remind me of the cheapo, black, steel rims. I call that style rim "forever steelies", but they're nicer than no rims so decide if you like them, that's all that matters.
Start making it a point to hit up your local breaker yards. The 7th gens are plentiful and any parts you find in a sedan will swap right over to your wagon, besides the tail lights anyway. In the last 6 months I've found everything from the big center arm rest to OEM factory wood trim dash bezels and leather seats!
Also, look at steering wheels from the 8th gen Corolla S, they are black leather wrapped with red-stiching. I've found 2 in the last half a year at my local junkers. They're a more modern looking, 3 spoke design and they bolt right in. The airbags are different though, so make sure you clip pigtails off the clock spring from the donor if you find one.
Early to mid 1990's Lexus ES300 horns will swap over too with minimal modification, just make sure you get both the "L" and "H" tone horns and try to grab at least 2 wire pigtails so you can avoid cutting your wagon's horn connector.
If you have the loot and/or the skills and means, you can drop in a black-top or silver-top 4A-GE engine for a nice HP increase. Or you can buy rare JDM bumpers and lights and cool japan-only options like window sail tweeters, power folding mirrors, automatic headlights, ignition key light, all kinds of odd little things.
Anyway, start by looking at other people's build threads. Start reading what other people have done. Becoming intimately familiar with your whip and others you find in the junkyards is a good idea too. There is so much customization you can do. It'll keep you busy for years!