Try to do as many duels and 1v1's in BG's as possible. This will help make you a better player and increase your knowledge and ability to guess what classes will do in different situations.
I don't completly agree with that one tough I think you are better of just finding somone preff a friend to spam queue arenas with untill you get a basic view on what the other players/classes on your skill level do in arena and then work your way up from there.
Going BGs and duels is fine but it's just not the same playstyle in arena. The thing about what players do in different situations is really different from arena and duels/bgs since they have to think of your teamate/s aswell what can they do if I do this and what will happen to who then and what can be done to prevent that.
Dont really agree on the BG part, but duels for sure.