There are three levels. If you never played before, try the easy level first until you understand how to play it.
The game plays over 300 days. You have "missions" to settle every 30 days. The missions are random so don't expect the same missions every time. Solving the mission grant you a special "joker". Every week you will get a normal joker. Use it, otherwise it will disappear the next week and you get another joker.
The most important statistic are the charisma and refinement. You can increase it using experience. Don't forget to change the price after each week or you will be short of money. You can choose where the girl will work. At the initial stage, you get the shack which cater for 1 person, so don't be overzealous in buying other girls.
You have to be careful and choose wisely when using the joker. For example, since you have only one girl at the beginning, the 300 XP is not worth that much and I recommend you take the money.
Once she has some experience, click change price, then estimate. The stats can be increased by using the experience points. Mind you that different girls uses different amount of experience points.
Once you have enough money to cover your mission and extra, what do you do, buy girls, no, you should buy a house first. Then only you buy a girl. Don't buy girls more than the spaces in your houses, unless that is a mission, like have 14 girls before certain days..
After you buy a house, you got extra working space, har har..
When it comes to buying girls, try to get the one with high charisma or refinement and low character. If you just started, you can't go wrong with either of these girls.
If you managed to solve your mission, you will get a special joker. Please use the joker before the completion of the next mission. How you use the joker is also up to your choice.
Usually I asked for a girl, cause girls obtained from special joker have high charisma or refinement, depending on your luck..
Once a while, you should rank up your girls. Then their price increases.
Don't ask me how to level the girls to level 8, I managed to level up until 7 only...