Or get good at arena
Got any pointers?
Arena is dominated by decks that can play minions on curve. If you lose tempo, it's hard to comeback. So when you draft you want enough low cards to be able to play minions turn 2-4. Board clears are very strong, weapons are strong. Classes to play as are Rogue, Mage, Druid, Paladin and yes, Warrior isn't the worst anymore. It's actually pretty decent.
Each plays differently, but don't make the mistake of drafting amazing value card if you'll never get to play them. It sucks that there's no spectator mode for drafting, but like wero said, using heartharena is a good place to start. It's pretty good at drafting, but you need to sometimes be weary because it overvalues synergy in my opinion. Or at least it used to. Wero is also right that watching streamers helps with playing, if you can guess the play before they make it, or pause the video and see if you played the same. Essentially though you want to make efficient trades without losing tempo. Rogue is one of the ebst classes because she has tons of early removal spells like deadly poison and backstab that are high tempo. They cost very little and do a lot. You use up your cards faster, but many of my games in arena are decided by turns 5-6. You can go 10wins with a deck that only have one 6 drop and nothing bigger if you can play enough stuff that can't be removed.
Also remember that arena can be high variance. Sometimes your best play is to play into flamestrike, because you can not win any other way. If they have it you lose, if they don't you win. In fact, this is something that improved my play a lot. Try to see how you will win this game and how your opponent is trying to win the game. If they are spamming minions and hitting your hero, they are probably going to try to win as fast as possible and you can try to control their minions and heal yourself, but if they are making trades, they are probably playing a control game. You can't tell if a deck is aggro or control by the hero in arena. Remember that you are not trying to draft a constructed deck, you are drafting a tempo deck that plays minions on curve.
And don't play around cards religiously. Sometimes you can only win by taking a risk, especially if you're behind in the game.