First off, N.C.S.E., I have to commend you for having the guts to post your work online. It takes guts to do it, and you're one step ahead of me, because I haven't yet had the constitution to put myself out there like you have. So good on you.
I'm also doing my first biplane, which is also my first model. One thing I'm really noticing took my work up a whole bunch of notches was to get a pin vise and micro drill bit set to drill hole for the rigging. They can be found pretty cheap (I think I found my set for ~$5 CAD) and being able to pull the rigging wires through drilled-out holes like Bud instructed just takes the realism up 10 notches. It's really simple to do, so the cost/benefit works out to be very positive.
I've also found with my brush painting (and any painting for that matter) that careful, judicious masking, while super tedious, really helps details stand out. The Tamiya tape that you hear so much about is really nice to work with, and a good, sharp scalpel will really help you get nice, sharp lines. Just make sure the tape is pressed to the model with a blunt object to ensure that there's no bleeding underneath.
Looking forward to seeing your progression, young sir!
Lindsay