Great question, @Nadialuna! To be honest, my tarot journal is a scribbly mess 
But I think that just like with Dream Logs, it’s more about recording the experience than making it look gorgeous! 
I usually write the date and day of the week and the question I asked. Below that I write which card I pulled and which position it is in (depending on the spread, but usually just the 3-card past/present/future reading). I write a brief description taken from that oh-so-helpful guide book that comes with the deck (as I’m still learning the card meanings!). Then I write how I am interpreting these meanings for my own life and circumstance- how they relate back to the question I asked.
Then I can go back later and see how my interpretation matched with what really happened! Sometimes I go back and see that the card really did relate, just not in the way I initially interpreted it to 
. My goal is to eventually improve my reading accuracy, while studying the cards! 