Starting to track trades, what's essential for a journal?

Just started dabbling with options, mostly $SPY weeklies, and realize I need to get serious about tracking. Right now I'm just noting entry/exit and P/L in a spreadsheet, but I feel like I'm missing a lot of crucial data. For those of you who have a solid trade journal, what are the absolute must-haves you track that actually help you improve? Beyond the basics, what really makes a difference for reviewing your performance and strategy?