If you are experiencing a lot of failed transactions in your METAMASK wallet when trying to buy Cryptokitties, you need to increase the GAS price you are offering to pay.
You will pay MORE for transaction fees, but you are more likely to secure the kitty you are trying to win.
Try these settings as follows:
GAS LIMIT = 300,000
GAS PRICE = 30
Due to so many people trying to buy Cryptokitties it is forcing UP the cost of transaction fees. If you put a lower price, you transaction will most likely fail.
Good luck! we hope this helps you to win more kitties!