I finally had the time (:P) and decided to make this thread.

Why re-selling?

-energy free
-easy money
-if done well best crowns/time making

Cons:

-risk that u might lose money or just time
-more boring than JK runs (sometimes :P)

Safe merch:

even though re-selling to players have risks, re-selling to NPC's doesn't, cuz their price is fixed. So if u can get mats or gear below the NPC's price u can make profit without any risk. Now u think y would ppl sell below the NPC's charged price. Answer is they didn't read my thread. Some common items u can find below the NPC's price at AH are:

-haze bombs;
-gel drops, scrap metals, brimstones, ecto drops(ya, ppl sell them for less than 1 cr ea at AH sometimes)
-rocky cores
-brute cores
...

Recipes re-selling:

There's one re-sell business every1 does, buy recipes at basil and sell them at highier prices (this normally only works with 5* recipes and some 4* recipes).

Energy market:

Other common business is energy market. As u should know u can sell and buy bulks of 100 energy in the energy market, and that the one selling energy pays a 2% fee in crowns of the sold price. However since the prices fluctuate alot, u can easily just buy, and sell for more than u bought plus the 2% fee. To calculate it divide the price u bought the energy for 0,98, this gives u the amount u must sell it for to have 0 profit, so anything over that amount is pure profit. To make the price goes up, u can do 2 things either hit the auto-button or w8. To make it go down just sell for lower prices than the lowest.

So a good tactic to make money out of the energy market is make it go low, buy while its low, w8 for it to go back up and sell (warning to make this alot of money is required, so either be very rich or have a huge group of players).

Although u need alot of money to do this, the difference between the highiest offer to buy and the lowest to sell is normally highier than 2%.
So, what u can do is: post an offer to buy at the highiest current offer or 1 crown above, then u can post an offer to sell at lowest current offer or 1 crown below. If u do this u normally make a 10-100 crowns profit per 100 energy(not that bad 1 energy in 10 sec, nearly free of risk).

e.g.: As im seeing right now the highiest offer to buy is at 5900, and the highiest to sell is at 6035, so i go and buy 100 energy for 5903, then sell it for 6035. My profit is 6035 - (5900/0,98) = 15,3 crowns.

Another thing people do is buy bulks of 100 and re-sell them a piece at highier prices in haven 1, this normally has less profit/time than my last suggestion (because normally most people dont do this and just buy 100 energy).

Auction House merching:

This is where the tricky part starts, but the benefits to gain are way more. This is because of the 10% fee upon sale.
There's basically 3 strategies to trick bidders.

The one that doesn't require u too manipulate the prices is w8. In most of mats the prices differ during the day, because of the rush points. I'm not sure if the rush hour has the highiest prices or the lowest prices, since the sales rent instaneous. What i do know is when the items re cheaper and when they re more expensive. So what u should do is look for some items where the time of the day does change the price for more than 10%. Normally when the prices are the highiest is around noon till 4 pm and when they re cheapest is around 8 pm till 4 am (GMT zone time). The obvious to do is buy when they re low w8 a few hours then sell.

Another way is look for non-rare mats, but valuable (blue shards, green shards, fine fabric, bushy tail...), put the sort for buy price, and scroll down the list till u find a gap between the buy prices something highier than 8% should be enough. if u do and the price isnt too far from the cheapest one, what u can do is buy all the mats that are b4 the gap and then re-sell them with the 8% increase, it's true that all the 8-10% will lose u some money, but as long as u end with profit it doesn't matter.

Now this where u really trick the bidders, and where it really gets risky. The trick here is making ppl think the price for some mat is lower than the actual price. How u do that?
What u gotta do is fill the 1st page (one page takes 20 items) with auctions below the real price of the item in question, u gotta really fill a full page so ppl dont see a huge gap between your auction and the real price. After that what u gotta do is refresh the sort for buy price and buy any items ppl auction for lower than the one you did.
e.g.: fine fabrics re selling atm 620 ea. what im gonna do is post a full page of fine fabrics selling for 500 ea. then im gonna keep refreshing the page. once i see an auction below my price I acquire it.

That's it for my re-selling suggestions, i hope u like it and use it someday or that use this so u know u re not being tricked :P.