One way is to only offer annual billing, but couple it with a 30 day trial. Hubspot operates like this and it results in a more invested user and substantially reduces churn and lowers support costs. It lowers churn because of you are going to pay for a year of something, you are going to be really sure it solves your problem. This approach only works though if you have a clear product-market fit.
I would like to note that in my opinion 30-days is a bit long. It's more efficient to offer 14 days. This motivates leads to try your product ASAP without postponing at a later date. Some people ask to prolong their trial and we do it, but again, in general it helps.
