Each hatchling has their own set of adorable outfits. The best part about them is that each outfit you unlock gives you a permanent coin bonus to the end of each level. The more outfits you have unlocked for your hatchlings, the more coins you'll earn! Each hatchling has two outfits you can buy with coins, but the others must be found from the chests. It's expensive initially, but you'll be earning lots of coins in the long run!
Premium chest!
The Premium chest costs 20 gems and has 2 star outfits, random currency, and random boosters. Try to save your gems for these, as the outfits are the main things you'll want. More outfits means more coins in the long run - remember that! That also means that you'll be able to open the Basic chests more often too! If you're lucky enough, you might earn some of the gems back.
Various Gameplay Tips
Tip 1: Try and focus on the items that are going to let you pass a level.
Tip 2: Don't just make the match the game suggests.
Tip 3: Try and save your boosts for when you know you're stuck.