DIY.Solar panel info

Have been reading many threads,My First paneling building.I bought 72 cells 3x6 @ 1.8 amp. What is the best way/how many in each string/and end voltage of panel. I will be charging one 12 volt deep cycle auto battary, I thing it's about 180ah.I plan to build more panels to add to system. I have been told of SOOOOO many different "out put voltages they should have." Im thinking output of 18vdc.
thanks
Johnny