It is much easier if the fit between the two pieces is tight. You want enough glue so that it gets into any crevices and covers the whole area without leaking out and coming into contact with other parts, particularly leather and ribbon where it creates an obvious shine. A little glue can travel a long way! The slower you go the more chance you have of fixing problems before they become permanent.
Glue generally works better on uneven surfaces than on smooth surfaces, so roughing up the inside of findings or scratching a ridge for the glue to be trapped in can help in bonding smooth materials.