I agree about managing expectations. It is one way to get tons of lixes idols and pots. Sell or trade the ones you don't need, and try not to buy them at the highest price.
When you get a charm, or a little plat, or gold enjoy it as a bonus. If you get a mount consider yourself extremely lucky.
Do not buy 1 or 10,000 chests with the purpouse of getting a mount in mind, as many do. That is most often NOT what is in a chest. The chance of a horse is the same on the 1st one as on the 10,000th one. If your main goal is a horse, sell the chests and buy one with the gold.
Finally, as with any game of chance. Set a limit before you start. If you have $€£¥10 buy that much plat, get that many chests, and stop. If you can spent 1000 in real life currency, set that as a limit the same way. I enjoy spending some money on chances periodically, but I enjoy it the way I would going to a movie. I will not come out of the movie and go buy 10 more tickets the same day. Gambling can be addictive, and it is a lesson folks should take seriously when doing this kind of thing.
*steps off of soapbox*
GARAT level 198 Ice Mage
Started playing at the beginning of Sahmain 2012
The Mage's best weapon is a calculator!