Pre-60 is going to be difficult to farm.
I would recommend heading out to Azshera and farm felcloth at the Saytr camp. There is one in Felwood also but there is more traffic.
I did that for a few levels and you get felcloth for your prebis pieces and good gold.
Once you hit 60 and get into a few pieces of your prebis you can farm in a number of places.
You can farm Mara and kill three of the bosses.
I average about 10 minute runs with all three pulls.
You can do Mara in prebis greens you don't have to be decked out. It's not hard once you know the path and different techniques. One thing that does make it basically 100% success rate even if you get bad rng on princess is peasants collar.
You can also farm DM: EAST but you will need to be in decent gear.
Can also farm Eye of Shadows.
Hope this helps.