(Dust and glue residue are released during sanding. Wear old clothing, eye protection, and respiratory protection, and vacuum thoroughly after sanding.)
Use coarse sandpaper to remove the glue residue.
Use fine sandpaper to get it nice and smooth.
You’ve now finished the various parts of your project. However, it doesn’t look good with all those glue seams and glue blobs.
Time to sand everything nice and smooth. You can sand large surfaces with sandpaper and a sanding block.
I personally find the Dremel a handy tool; it allows you to quickly sand all the seams and round the edges.
(Don’t sand in one spot for too long; it gets hot and can cause the glue to come loose.)
After sanding, dust your part with a brush. Sometimes you might not have glued something properly or there might be a visible seam. You can easily fill this in by applying liquid foam to the seam with a brush and then sanding it again.