I like QSL cards with this style: single-sided, with concise QSL information directly written on the front.
Recommendation:
1) A field to enter the other party's call sign, for example:
To Radio: ______________ CFM OUR QSO / UR RPRT
CFM contact with: ________________
2) DATE should be left with a reasonable amount of space, as "year-month-day" is the longest format.
3) The typical order for QSL elements is DATE, TIME, BAND, MODE, RST. If necessary, the PROP field can be added to indicate special propagation methods such as EME or SAT.
4) Leave space for a short message and signature, such as:
Thank you for the contact, 73! Quarix
First contact, 73! Quarix