How many images are you going to capture? I usually shoot between 300 and 500 images per day, if I’m inspired, the number goes up, if I’m really inspired, the number goes way up.
What file format? I shoot RAW, always! This means big files, think 32, 64 and 128GB cards. If you shoot JPEG, your file sizes will be smaller so you can get by with less storage space, a 32GB card will hold a few thousand 6MB pictures.
At the end of every day, I off load images from the memory cards to the external drive and backup to the cloud or to the second drive. Getting those images was expensive, don’t skimp on backups. Internet speeds can be slow in some places so cloud storage is not always an option.
A note on shooting RAW.
RAW gives you more options in the processing and editing phase. RAW takes up more memory but cards are a lot less expensive than they used to be. I shoot RAW on all my cameras, including my cell phone. RAW files can’t be altered easily, so processing doesn’t destroy the original as can be the case with JPEG if you’re not careful. It’s also why some competitions prefer or require a RAW file so the judges can see how much the image was altered, dropping in a more interesting sky would be obvious when the original is examined.