Another wonderful guide found on the amazing Fashion Wars Official Website:

*Get 500 posse early by level 20-30. That will protect you for a while and doesn’t cost upgrades. Use big posse instead of style/att upgrade early on
*Start off adding to energy and stamina up to about level 40 so you have leveling ability. Maybe 50 energy, 33 stams.
*Levels 40-45(50) Get 125-150 health
*Levels 45-70 Add style/att equally. You go on top fightlists at level 70, so continue adding S/A all the time.
*Levels 70-100 Adding to S/A equally
*levels 100 + Try to get 200 health as a minimum fairly soon. Increase styl/att equally at every opportunity. Increase stam/energy if you are away from your comp for long periods in the day so they are not filling up so often.
After level 200 some people just increase S + A. Others increase Health, S + A. Aim for S + A = about your level 50-100, 1.5 times your level 100-200, twice and more times your level for level 200 +
I have 120 energy, 74 stams so they don’t fill for 6 hours, but that’s probably too much for most people espec early on.