Yeah, practice will help you a lot. As for practicing in duels, keep in mind two things. First, a duel isn't going to properly represent what you should do in arena. It may help you do damage to people, but that is only one of the three major facets to a Ret. Second, don't play to win. Instead, focus on practicing certain strats for dealing with people. If you happen to lose, just means that person is more likely to duel you again so you can practice more.
Your #1 priority is staying alive at all costs.
Playing with a Hunter and Feral, you have to be able to support your partner. That is your #2 priority. Try and help protect them from enemy burst (CC can be used here if necessary) by using your healing and utility skills. Hand of Freedom, for example, is particularly strong for a Hunter. All of your hand abilities, healing skills, Sacred Shield, Cleanse, etc. so on and so forth, are very important to your partner. You have them for a reason! Use them!
The last priority, which is attacking your opponents. You can regularly hit people with Judgment (especially if Judgment of Justice is necessary) to help keep your mana up. But otherwise, you will be hiding from the enemy - or trying to, until their damage CDs are gone. At which point, you can go more on the offensive. Use your Avenging Wrath to help secure a kill with the help of your partner. Never use it to try and force someone to get low, as it has a chance of backfiring. When fighting a double-DPS comp like Rogue&Mage for example, you win by out-lasting your opponent.
Or at least that's what happens at competitive-level. If you severely out-class your opponent, then by all means, go and YOLO them to your heart's content.