Around June remove the flower heads as they fade and cut out the flower stems of about 50% of the faded flowers. This will encourage a second flush of flowers in the autumn.
Mexican Orange Blossoms have no special pruning needs you can simply prune to the shape and size you want each year after flowering.

If frost has damaged the plant badly, it can be cut to 25cm (1ft) from the ground and it will grow back over the next few years.

April is the time to give it some bone meal and well rotted manure.

I might have asked a more detailed question: Do I thin out multiple blossoms on a stem of a real orange tree? How many may I leave per stem? Thanks!