User blog comment:Manushster1/please help me manage my units/@comment-26336535-20151225232521

My advice: Never sell a unit if it's the first time you summoned it. Sell dupes all you want, but that unit might become useful. It usually becomes apparent when trying a Trial or GQ when you might want/need more units who do the same thing. However, for old units that don't have 7*, they might get one, and it might be OP as hell.

If you haven't gone through all the Quests yet, charging through that as quickly as possible and logging in everyday (just open the game and collect the daily reward) can get you a lot of gems. Spend some more Gems on your unit capacity; it doesn't hurt to save space for Evo mats and Metal Gods or Crystals.

Once you get far enough into the game and have the units you want, I'd recommend raising some dupes for fun. I just got my 5th Hadaron to complete my Mono Hadaron squad that has been sitting with Krantz in the 5th slot, I'm preparing a Quadruple Rahgan + Selena squad for Arena, and I've got plenty of dupe units for Grand Quest and Trials.