Wall work on big holds strengthens finger tendons, which will help stave off injury when you re cranking on real rock. It ll also build the forearms, lats, abdominals, pectorals, and back muscles you need to defy gravity. Practice getting into resting positions, so you can hold on with one arm, and shake out the muscles on the other. Practice for routes Indoor roped routes are much more straightforward than anything you ll find outdoors, but some skills are easily transferable. Even if you are planning on outdoor crack climbing, you ll still have to clip the rope into carabiners after placing gear.
Indoor gyms are a perfect place to perfect the art of clipping.
Work on smooth delivery of the rope to the carabiner and make sure the rope is clipped in the right direction, the first time, and every time. Leading indoors is relatively safe, since the bolts are placed in close proximity of one another. To transfer leading skills outdoors, try to lead as many new routes as possible, rather than sticking to the ones you already have wired. The scariest part of leading is getting above your protection. Look for gym routes that allow you to get your feet above your gear before clipping the next bolt.