I just downloaded the game a few days ago and I still a bit confused of how to play. I am at day 12 but still stuck at mission of creating Lust Potion (day 10 teacher letter). I uncovered Lizard Tribe Ruin but I have no progress at all with money and level. Any tips to gain more level and how to get ingredients for Lust Potion Mission?
You can find succubus leaves at the swamp, which will help with the lust potion mission.
Beyond that you're actually okay! Just keep exploring around, as that's a lot of the fun of the game. If you're only on day 12 then you have a ways to go before most of the big moneymaking options really open up, but you can get money from defeating bandits (Particularly beating them up), doing odd jobs at the tavern at night, or helping the Shopkeeper in Bareshade.
You gain levels by beating things, when you're that early really defeating whatever will do it for you.
Don't forget that you have a Quest Log - it's under the heart section of your menu and helps explain where to go if you're stuck.
The higher your intelligence (and perception) the better your odds of finding more rare things.
That said, my intelligence and perception are nearly minimum, haha, so it becomes 'just keep at it'. Strong good looking herbalists are more patient and stubborn. :D (I do have a little bit of gear boosting them so they're not /actually/ minimum)