You can prune it any way you like, but why now? Many of the small branches will die over the winter, if you want to make it a neat plant, good luck. Some years they can look bad for a couple of months in the spring, but the new growth will cover all that. If it is a new vine, then pruning it back severely in the spring can help it. What I do is leave the part on the wire support alone, and every couple of years I reduce the amount of bulk there. The vine, once established, takes almost no care, but it doesn't mind pruning either. This is a good sturdy native that can take almost anything except dry sunny windy conditions.