Signs, releases and lease agreements are all good ideas but they will not prevent someone from bringing suit against you if they are injured on your property. People can and will sue you if they are injured, even if they are tresspassing. What you need and want to have if someone is injured on your property is a good liability policy. Most property owners can add their farm & ranching interest to the liability portion of their Homeowner Policy. In Texas most Homeowner Insurance Companies will let you have a limit of 500k to 1 mill in liability limis on the Homeowner Policy, you have to ask for these limit, they are very inexpensive and reasonable. On top of that you can purchase and Umbrella Policy in increments of 1 million dollars that will go over the limits of your underlying Homeowner Policy Limits.

Some VERY IMPORTANT points to ask your Insurance Agent are:
1) Are Defense Cost and Attorney Fees in addition to your liability limits?
2) Be sure your Homeowner Liability and Umbrella Liability Policy do not exclude Farming and Ranching interest. Some Policies do, READ YOUR POLICY and ask your agent.
3) If you have a business venture on your property or charge people to come onto your propety for fishing, hunting, horseback riding etc., you may need Commercial Liability Policies instead of just your Homeowner Liability Policy. Most Homeowner Liability Policies exclude any type of business venture. In this case you would need a Commercial Liability Policy with a Commercial Umbrella Policy.

There is a big difference between Commercial and Personal Libility Policies and Umbrella Policies. Be sure your agent knows exactly what exposures you have at your place and address them. Don't be cheap. You want to be sure you have the correct policy should you need it.