First of all, you may ask "What is an Ante"
It is the card you want to bet on to take over give away when battling another duelist. Now if you defeat the other duelist, you'll get the card he bet on. If you lose, you lose the card you bet on.
Now, you might want get rare cards when betting and winning. How do you do this
Well, it's quite simple. Bet a rare card, and make sure you know the risk you are taking. The rarer the card, the rarer the card your opponent is going to bet. Just make sure that you think you will win, or else you have lost a rare card.