DragonVale tips I wish I had before I started.
Do not waste your gems in the tutorial. Upgrade your hatchery instead.
Buy as many plant habitats as you can and fill them up for quick gold. Don't bother feeding your plant dragons too much. Plant habitats fill quickly then don't earn more. You need to check your plant Habs every few minutes.
Always keep your habitats full. Even if you need to sell dragons later, in the mean time they will make you money.
Most of my money came from four fire habitats. Again, keep them full with cheap dragons and sell them when you run out of room.
Earth habitats are your overnight bank. When you sleep, they make the most money. Overnight, plant habitats are useless.
Pay attention to your market and make sure that you buy the maximum number of treat farms and habitats for your level. Even if you have to sell a habitat later, it can earn you gold in the interim.
Always buy a small habitat, put a dragon in it to earn money BEFORE upgrading to large. A small earth Hab takes 5 min to build and costs 100g. It costs 2500g and 24 hours to upgrade, and will earn money in the mean time. A large earth Hab will cost 2500g and 24 hours to build, and will not earn you money while building.
Breeding. Look to the fast breeds before the slow breeds. Air dragons take two hours to breed and two to hatch, and are much more useful than a crystal dragon that takes 24 hours. Especially if you ignored my first tip and didn't upgrade your hatchery. I can't post the link, but there is an excellent googledoc of all the eggs, google it!
Pay attention to the storage capacity of your Habs.
Plant > Lightning > Water > Air > Fire > Cold > Earth
Always put your hybrids in the larger capacity Hab. If I see a high level Tree or Moss Dragon in a plant Hab it almost makes me cry for the waste. There should be no hybrids in plant Habs ever, just low level plants. 4 Adolescent Plants are enough to really pump a large plant Hab.
Coliseum events are won by dragons of the flagged element.
Bronze; Adult dragon, similar element.
Silver; Adult dragon, same element.
Gold; Level 10 dragon, same element.