Honor Hold and Thrallmar
Honor Hold and Thrallmar are the first reputations a new player stepping into the Outlands will encounter. These two reputations are very easy to raise. Honor Hold and Thrallmar's main quest hubs and reputation hubs are both located in Hellfire Peninsula. After you finish all of the quests in Hellfire for these two factions the only way left to raise your reputation will be by running Blood Furnace, Ramparts and Shattered Halls. If you'd like to see the quest involved in getting the Shattered Halls key, click here.
You will only gain reputation from running the normal version of these instances until the end of Honored. Unless you are running Shattered Halls. Normal Shattered Halls will give you reputation all the way up to exalted. However you will need to run Heroic Ramparts and Bloodfurnace to gain reputation past honored.
The Honor Hold and Thrallmar reputations have Marks, which you can acquire through the PvP dailies. The PvP Daily requires you to capture the 3 locations in Hellfire. Generally they aren't worth doing and no one ever does them. However, if you want to you can feel free to do them. One of the items you can buy via the Marks is Thrallmar Favor and Honor Hold Favor. Both of these items will increase the reputation you gain while running an instance by 25%.