What is the best way to back up data from my Macbook?

My Macbook is pretty full and I need to get some stuff off there.I am currently backing up all my photos and some of my music (that which I can't live without) on IDrive but I don't want to delete them until they are copied somewhere else for redundancy. So from my understanding an external hard drive is probably my best bet, although since I'm mostly just concerned about pictures and music I guess I could just buy a couple of USBs. I was trying to read up on hard drives and find out who makes the ones for WD and Seagate coz then I could just buy it and an enclosure for less, but I got lost in a sea of RAID 0's and SSD, and now am more confused than ever.