I use a tiny drill bit to make a hole in the centre of either side of the damaged joint, then cut a piece of metal tubing (hobby shops sell them) or a piece of plastic such as filament from a 3D printer (getting a ~1cm piece of PLA from your local library is probably free) to use as a pin to fit into the holes and reinforce the joint. Then once you are happy with the fit, glue it all together. If it is really tiny, you may not be able to pin it and then glue might be your only hope. Depending on the weight of the parts and material, crazy glue is usually pretty good for most situations. With plastics, where I need it to grip right away and hold its own weight, I like Testors modeling cement. Way better initial hold than even the gel crazy glues.