By far the best way to make adena is buy item specific materials (IE emi bow shafts) and/or recipes (b grade and above crafts), then setup buy shops for all the base mats required for these items below market value but at a competitive price with other buy shops. Do this while you are sleeping or gone for the day.
Emi Bows are the easiest as it only requires 5-8mil initial investment and you can convert them to any C grade weapon thru mammon to sell. You can turn a good 3-5mil profit per emi bow, depending on your server and current material prices.
Takes practice and patience, but as you make more you can buy more and craft more and thats when the profits mutiply.
If you need advice on the quickest way to lose adena, start enchanting what u craft past +3
