Most of the problems for new players in Arena 4 or Arena 3 is the X-Bow, a acrd that, if you put it on the top of your side, it will start to take a big amount of hitpoints from your opponents tower.
For me, the easiest way to counter a X-Bow are the troops or cards that target directly defenses, like a Hog Rider or a Giant, along with a splash damage troop, like a bomber, a wizad, or a dragon; with this troops you will create a squad that not only destroys an X-Bow, but you will create a huge offensive push to earn a crown.
The cost is low, for example: A Hog Rider, 4 elixir; a Bomber, 3 elixir; and if you want to add power to you push, you can wait till you have 10 elixi for trowing an esxtra 3 elixir card, as a Knight, or a little bit more for a mini-P.E.K.K.A.
Hope this strategy helps you aon these arenas,
See you on the next post.