A good glue job is as depended on the preparation as the glue.
Slightly rough up the surfaces to be glued.
This makes more surface area for the glue to adhere.
Clean the surfaces with alcohol that is pure, not rubbing alcohol, as it has oils in it.
Make sure not to touch the surfaces with fingers as they are oily, too.
Apply some pressure to the glued parts to assist adhesion.
As to the type of glue, pick one that is compatible with plastics and polymers.
Hope this helps, some.