Keep in mind you are working towards two things when you hit level 40
You should be making more Mabinogi Gold than enough money to pay for new skills, updated armor and weapons, gryphon flights, stupid noncombat pets (hey I love me too!) etc. But keep in mind you are working towards two things when you hit level 40:
1. Buying your mount which is going to cost you 90g
2. Preparing for your first crafting profession which will take money to level and buy schematics/patterns/recipes/etc.
You cannot enter Phase Two until you have purchased your mount and have like 100g in savings. Trust me on this one.
If you are relatively low level but have a mid-level crafting professions, I would still drop it and take up a second gathering profession. You will end up making much more money by the time you are 40, which is the real goal of this guide.
The best thing you is get a general idea of how much stuff is selling for at that time, price your materials a little bit less that that, and hope for the best. Do not throw your hands up in despair when someone undercuts you, it is going to happen.
Just take your unsold mats and put them back on the AH someone will buy them, trust me!