I have been a coworking user for 3 years (not an operator). Local Marketing by Experience is what you need to do. By this I mean get visitors to the space and pitch them when they are there...

My advice is this
1 - offer the space as a meeting venue for Meetups locally. Get people visiting the space through meetups and ask the organiser to allow you to pitch all attendees about the available space and "special rates" for their members.
2 - Research highly networked people you know and ask them to help you publicise on social platforms. Ask them to occupy the space free of charge on the condition that they use your space to host their meetings - so they bring people in.
3 - Offer the space short term for the use of local business incubator (they typically run Lean Canvas startup programs for 8 - 12 weeks). This gets visitors in the space and it looks busy... again, you achieve the objective of getting people in and using the space and used to visiting.
4 - Review your pricing. Find out why visitors choose to go elsewhere and if it's price - adjust accordingly.
5 - Review your offer. Can you offer Co (collaboration) and Working (shared workspace)? Most only offer workspace. My advice is to proactively manage the collaboration part. How can you introduce workers to each other, now can you facilitate them winning new customers in your space, how can you leverage your networks to help them win business... How can you use your platform to help them sell more. If you do this, people will want to use your platform for their business and the condition for that is to pay you to occupy your workspace.... problem solved.

Although all these tactics can work, my view is that the last one gives the most opportunity - but it takes work and is possibly hardest to deliver on quickly.

For more tactical marketing execution guidance, hire me and I'll teach you how to deliver.