Level 1 of Repair should bring the durability up to 60%, rounded down to the nearest integer, and each level increases it by 10%. Level 5 is required to repair broken items with 1 durability.
Keep an eye out to equipment with a Repair bonus; I invested 2 skill points myself, and found 3 items with a Repair bonus (a Ring, boots and gloves). Pickpocket and Identify are also handy to have (though I maxed identify anyway). I used a couple chests at my base to sort out full durability equipment to be sold and stuff that needed to be repaired (to get the maximum value for them; not that gold is hard to come by after the beginning).
Tutorial-Changing F1-F12 hotkeys to different keys
