Water based glue works best with paper models, PVA white glue is ideal.

The problem with water based glue is that it can soak into the paper and make it crinkly. You'll need to use it sparingly.

Spread a thin layer of glue on one surface only. Line up the parts to be joined then nip them closed to speed up the drying process.

To make sure that your folds are sharp and accurate you'll need to score them. Scoring is the process of making a dent in the card where you want to the fold to be placed. 

There is no one specific tool for scoring, the point of a pair of scissors works well, so long as the scissors aren't too sharp. You could also use an empty ballpoint pen or the end of a metal nail file.

Run the point of your chosen instrument along the line you want to score. Press down but make sure you don't cut through the card. Use a ruler if you are scoring a straight line.

Tips and tricks for getting the most out of your paper engineering