Once you've soldered the boards together it's time to neaten them up. There are a number of things you can do.
Remove excess flux:
Flux helps the solder flow and make good contacts however it does look pretty nasty when dried and is best getting rid of for that beautiful look. The best way to do this is you dab at the board with a rag which you've soaked in acetone. Where abouts would you get acetone I hear you cry ? Well you can get it some art shops, you can also buy it at some boating/marine shops as a part of the fibreglass range, however the best source is in fact cheap nail varnish remover. So head down to your nearest cheap pharmacist and start looking for the cheapest nail varnish removers. I'm talking about 49p for 200ml, my past experience shows that this comes in pink bottles.
Clean up the edges of the boards:
This is as simple as sanding the edges of the board down so that they're smooth and flat. It's also quite nice to round the edges.