When you're leveling up, just take the pieces with highest main stats. How you do it on xivdb is to specify the piece to have the main stats like say Strength when you're building a set for monk or Craftsmanship OR Control (see that check box with AND and OR?) when you're building a set for Armorer. Then set your level, like if you're 41, anything between 37 and 42 can be considered.