Red moko grass can be highly profitable, given that the price for a stack is high enough. And as you skill up harvesting (even though you don't see it skill up, it does) it will become more and more common. You might also try mining in places like Gusgen Mines or Yughott Grotto too if Giddeus is too full of other harvesters.
And for mining I suggest you start in Yughott and then move on to Gusgen a while later. However, only go to Gusgen when you have plenty of experience in mining and when your level allows you not to get aggro there.
And lastly, remember to mark all harvesting points/mining points you find on your map so you don't have to guess where they are later. But eventually you'll memorize it

Good luck!