It helps if you are familiar with the venue, or if there is a detailed seating chart. After that, consider how the band will be arrayed on stage. Not fun to be up close, but on the wrong side of the stage, and you spend 90 minutes craning your neck to see.
p.s. First row is not always the best place to sit. (I remember going to see Taj Mahal play at the Bottom Line in NYC. I was seated at a table right beside the stage, but when he played the piano for 1/3 of the show, I couldn’t see anything but his legs/feet.)