Choose a non-peak date. If possible, try to be flexible with your wedding day. Most venues will be significantly cheaper midweek or outside of the summer months. You might even save money by choosing Friday 13th or April Fools' Day!
Reduce your headcount. The more guests you have the bigger the venue you need - not to mention food and drink! Do you really need all those plus ones?
Throw a tea party. There's no rule that says weddings must run into the evening. Finding a venue that will do a simple afternoon spread of tea sandwiches and sparkling wine is a sophisticated (and cheaper) alternative to the typical wedding breakfast.
Consider a non-traditional venue. Rather than a dedicated wedding reception hall, check out less expensive facilities with licenses, from city-run spaces like zoos and gardens to restaurants or more offbeat locations.