Here are some safety tips from Consumer Reports:

Check the propane tank for any signs of rust, dents or any substantial corrosion. If the tank is not 100% you should replace it. There are LP tank fuel gages commercially available and are very easy to install. In the absence of a gage, you can remove it from the grill, stand it upright and poor hot water around the tank. The line of the cool area will indicate how much fuel remains in the tank.

You should carefully check for leaks, not only at the beginning of the season but periodically throughout the season. Dishwashing soap in a spray bottle is very effective in locating leaks. Spray the solution along all lines and connections. Any bubbling will indicate a leak. Remember, Propane gas is heavier than air and will settle (pool) to any lower area around the leak thus making it extremely dangerous.

The entire inside of the grill should be thoroughly cleaned of grease and debris. There are cleaning solutions commercially available for this purpose.

Cleaning your grates after each use simplifies the task as the grease will come off much easier when hot. Use a stiff grill brush if available. If you do not have a brush, crumpled tin foil will do the job.

Cleaning the exterior is best done when the grill is warm. Mild soapy water and a sponge will do the trick. A nylon pad can be used on tough areas.