I must agree with many of the posts already made.
1. Upgrade Your Web Site. It helps to sell daily for anyone who looks at it. Future Students always look at Greek Life Sites.
2. Build with in and make the Chapter stronger.
3. Recruit instead of waiting for formal rush. My Chapter was down to one Active and We had two ELCs come in for Recruitment. They did a tremendous job.
4. Wear Your Letters Proudly and if not daily, at least several times a week. Promote Yourselves.
5. If You are doing a Charity Event, get the School and Local News Media involved to help promote it.
6. Be a leading Greek Organization first and fore most.
It sounds like Your College is about the same size as My Alma Mater, @ 6,500.
We have 6 Fraternitys and 3 Sororitys. It is out of quilter size wise with @ 50 Members of Male and 75 for females Organizations.
Work hard, keep your noses clean, recruit the cream and You will grow!
Be leaders, not followers.