What study and financial tips would you recommend for a freshman who is interested in double-majoring in business and law at a four-year university?

I am a freshman in high school and am interested in double-majoring in business and law at a UC, though I am aware that I will have a bigger workload and my cost of tuition may be higher since I would have to attend university for extra years. I want to know some tips or programs that could help me study better in order to handle my workload. I also want to know of some financial tips so that I can handle the extra costs.