Don’t ignore energy efficiency improvements you can make to your home. They help reduce energy use, and perhaps even the size and cost of any solar panel system you install.
Don’t rush to sign a contract without thoroughly reviewing it. Make sure you understand if your costs for the system will remain constant or will increase over time.
Don’t rely on one source of information regarding assumptions on returns on your investment. Check things like estimates for electricity cost increases over time, compensation (if any) for electricity returned to the grid, and other assumptions that may impact your potential return on investment. Make sure to compare those estimates with other independently-sourced estimates.