Always read the instructions - twice!

While studying how I was going to mask the nose of the submarine (so I can paint it red) I discovered I had forgotten to attach 2 pieces : the forward diving planes. (Feel free to correct me on the technical term)

Here we discover another advantage of airbrushing instead of handbrushing. The layer of paint on the model is really thin. This makes it possible to 1) paint an entire model with a few drops of paint, 2) leave all panel lines and other details intact and 3) makes it very easy to scrape away paint where you want to attach a piece, whether you forgot to add it or wanted to paint the base model first before adding details.

(The main reason to do complete assembly before painting is that glue sticks better without a layer of paint in between. If you've already painted it, scrape away paint where you want to add pieces. Don't forget to also scrape away paint on the back of the piece you're about to add, so the glue has all possible chance to bond thoroughly.)

Gently scraping away paint where the diving plane will be attached.

Since I wrote the tip about superglue (found here), I started applying this tip also for regular glue.
In this particular case, if I were to add glue directly to the hull and accidentally apply too much, it would damage the paintjob, or at least leave visible marks of my clumsiness. By placing a drop of glue on a CD and then gently dipping the piece in it, I have a much finer control over how much glue goes where.

Place a drop of glue on a CD, then dip in the piece to be attached.
One single CD will probably serve several years.

I turned the sub on it's side, using it's own display stand, and put the port fin in it's place with tweezers (after dipping it in the glue). I did the starboard side only 2 minutes later. I really like how fast the glue becomes strong enough to handle the model without the freshly attached piece falling out of alignment.

(I'm using "UHU Plast special" liquid cement with a needle applicator. Revell has a similar bottle, also with needle, with probably the exact same content. I try to stay away from the "regular" less-liquid glues.)