I use a magic eraser with lots of summertime windshield washer fluid (bug wash). Wipe with microfiber. Takes off marker that has been on for years in the sun.
My usual order of product application for my daily driver is as follows:
Clay/Duragloss 501/Collinite 845 in the spring and fall. Seems to work well for me. I was impressed when doing some over-spray removal by Meguiar's Ultimate Compound and Polish and the depth of color it seemed to add to...