Here are some tips, coming directly from the design team, about how to maximize the use of Sanctuaries to obtain creature DNA. 

• Use all of your Care items in your Inventory. 
• Make sure you collect as many Care items as you can every day, such collecting from multiple Supply Drops. 
• Press and hold Care buttons to see a preview of your rewards. Use it to check which combination of care and creature will give the most DNA or Sanctuary Points!
• Level up your Sanctuaries as much as possible.
• Use powerful creatures (high level and high rarity) to gain more Sanctuary Points and level up faster!
• Join an Alliance! An Alliance allows you to cooperate to level up your Sanctuaries as much as possible before they reset.
• Ask your allies to place the creatures you need in Sanctuaries you can access via the Alliance chat.