For me personally, it's better to use something that allows the use of tags. Otherwise, it would be too much to go digging through later when you want to refer to an old entry.
I keep mine on an online blog platform. It's free and all entries are set to private. I tag every entry with the name of the card, the numbers, and whatever else I want to track.
That way, if I get a card I haven't seen in ages, for example, I can click the tag and it brings up all entries where I got that card. I can see how I interpreted it in the past, how my understanding has evolved, think about how it actually played out in life, etc. Also, I can use little pictures of the cards as icons. It works for me.
I also have a journalling software program on my computer, but I do not put tarot readings in it for the most part. It's called LifeJournal. You can make up your own categories and subcategories of whatever you want for tagging entries and use it the same way. You can insert pictures and links. You (can) set a password and your entire journal is encrypted on the hard drive, so no one can go snooping in it.
It would be very good for tarot journalling if you wanted to set up all the tags. (Or you could just use the search function. Tags are great though.) You can also make separate journals within it, with different logins, if you want to keep a separate personal journal. Or just let them all mix together. lol It's totally up to you.
Hope that helps. Have fun!