1. Can you find out what other investors are renting their places for near you and are you on the high side, so they may go for something more in their price range. Can you offer a more competive rent, as tenant turnover is one of the highest costs for landlords. If you can do things to have a tenant stay longer that helps your bottom line a lot. One landlord friend of mine, could not do a montly discount so he offered that if they paid on time every month and kept the property in good condition throughout the year, he would offer a nice discount in december. This meant he was only doing it one month a year, it gave his tenants something to work towards. They felt like it was more a holiday thing so it made them feel more like he was treating them like a friend or family member and not just a tenant. It also helped them out the most as they tended to stress a lot at that time over christmas or other holiday gifts and a discount in rent at that time made really happy tenants.
2. What is the demographic of the people that usually rent your place? Are they students so they are likely to leave? Are they older but many are in a similar profession? Some investors I have found have trouble when the area many of there tenants come to live and work is not as desired as they hoped and so move elsewhere to work somewhere better. If you can advertise in a place that might attract empty nest tenants, they tend to stay longer and take care of places better. There is a trend now where they are down sizing and moving to urban areas. If you can market your place to this demograhic, you could get a tenant that is interested in staying in one place for a longer period of time.
3. Do you increase rent during a lease period. Sometimes a landlord may not have a choice, but if a tenant feels they have been a very good occupant of a home and then the rent gets raised while they still live there, they see this often as a penalty no matter how good your explanation. I try not to raise rents on current tenants unless they have been there many years and costs have changed a lot. Doesn't sound like they are staying enough for this to happen, but throwing this out there in case this happens.
4. Can you offer some kind of bonus for every year they stay? Sometimes outside the box ideas can go a long way. Like if you have a friend that owns a local business and you can get them a discount for being your tenant as one example. Helps your friend get some loyal customers and helps the tenants see extra benefit from renting from you. A benefit they are likely to tell others which also will create word of mouth for your friends business and any rentals you own. Meaning it will be easier to rent places quicker as you offer more than just a roof over their heads. My first business was settting up fusion deals like this, just never got the chance to do it for any real estate investors.