Ideas I have

Without knowing much about the game, here are some ideas that I have not tried yet but I think should work.

Get a list of common crafting mats. Either gather them or buy from the broker in bulk. Then go set up a shop near the crafters. Start with a competitive markup but over time make it more aggressive. Get them use to the idea that when they see you, you will have the mats they need. If they dont have to run to the broker then you have a customer. You can justify higher prices for the time you save them and the fact they can buy exact ammounts. Not the mixed stackes they get off the broker.

Watch the DE market. Search for gear thats selling very low and break it down and relist the enchants on the broker. I expect to see a huge market here someplace. It can be a lot of work checking the conversions or watching for low priced things. I don't have any good idea to do that yet, but once I get into this market later on I will figure it out.

Use more alts. Take the time to level all your slots to 10 and get them to the first city. This will let you break large stacks of things down and sell them in smaller stacks much easier. Also having them close to the bank will make it easyer to save extra stuff to them.

Watch for trends in the broker. Some things will sell better to the leveling crowd and others to the raiding crowd. And by leveling I also include leveling professions. Some of the best selling items are those used for leveling professions by higher level players. The ones that do not want to take the time to gather them. This also applies to the raiders.