Always post a buyout price on your auctions. Don't think that "They'll just bid it up anyway." Many players will not bid on an auction with no buyout price unless the item's bid price is heavily discounted to begin with. This can lead to bidding wars, but in many cases the item will sell for a fraction of what you could have gotten if you had posted a buyout price in the first place. You will have more sales at a higher price and get your money more quickly if you post a proper buyout price.
I like to post twice a day, listing all auctions for 12 hours. One of my postings occur when I wake up at around 5:30 AM, and the other occurs when they expire, at around 5:30 PM. This allows me to always have my auctions up, and I am the cheapest for a short period of my server's peak. If you are unable to do this, a 24 hour listing, posted during your server's peak period will do just as well. Following this strategy allows me to keep my input minimal, at about 10-15 minutes per day.

You should try and quest efficiently - pulling several mobs if you can handle it, using your burst cooldowns while questing to kill everything faster. Many people would think that a 10-minute cooldown like Bloodlust is useless in open world, but you can do a "kill-15-mobs" quest in like 30 seconds if you pull a lot and use it. A free quest every 10 minutes is not that bad.
There's a good chance you can buy the raw materials for 25% - 75% of the going rate of the finished item, or mine them for free. The fee for an 8 hour auction is only 1 silver, so you can afford to re-auction rods that don't sell the first time. Be careful of making too many rods or other parts of a kind at once, though, as you may get stuck with them for a long time when others produce the same item and set a cheaper price to it.
If i start on a new realms, I am farming a lot of transmog from classic and Burning Crusade Dungeons and Raids. In the beginning, i start to post them if they have at least a DBRegionMarketAvg (Average value of an item on all EU realms of the last 14 days) of 500 Gold. All the other items get vendored. The time you hit a stock of 1000 Items, my value treshold raises to around 2.500 Gold. All the items below that value get vendored aswell. Newly farmed items that are above these treshold will be listed. Why? If I start over somewhere, I want to get a certain amount of gold quickly. Cheap items are great for that. Later on, to save time, Quality is better than quantity. As mentioned above, re-posting the items on the auction house takes quite a bit of time. At this point, I can recommend you the TradeSkillMaster AddOn, it makes your auction house work really a hell of a lot easier.
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