Semi aggressive isn't a bad set up to have if your careful. I would just remember a lot of the semi-aggressive tropical fish really are not that bad if kept in numbers. Also, remember to keep the adult size in mind when buying new fish (tigers can get up to 3 in). I missed your count right now but
the general rule of thumb is one inch of fish per one gallon, but I usually round up cuz I wouldn't want to live in a gallon if I'm an inch big, but that's just me. Finally, overfiltration is never a bad thing. This means if you have a 26 gal tank id get a tank rated for 50 gal. Just my opinion though.
As for plants, you can go with a variety of amazon swords, anubis (sp) or some ferns or mosses. Its really up to you as far as what you like so id say do a little googling on plants or even better check out the AA planted tanks section. As far as wood, I love it! And rocks too so just go with what you feel will look best. Oh and have fun with it, but as mfd said...more water changes the better
oh and, post lots of pics!