Is prostitution a valid choice to earn money ? I'm new to game
You have a good guide from an experienced player, and now I'll give you my two cents because I'm basically in your shoes and can offer the view of a newcomer. In my opinion, prostitution isn't the best source of income if you're just starting out. You don't have enough sexy, and you don't have enough money to jump through hoops to increase it, so you can only bang beggars and drunkards who give you little money. A notable advice: learn the buttons for each kind of sex, ASDF. It's in the notes in the game, and you press them during sex. I'm not entirely sure of the exact timing, but I press the corresponding button every time a thrust happens. The game shows you the additional trade points you earn this way, and it increases the total pay.
I personally prefer the dancing job at the bar as a primary source of income early on. Do everything except masturbation (spends too much stamina) and you will be able to buy a key for the room after each "shift" and still have some money left over to save. After each dancing session, if you have any stamina left and you've managed to escape an inevitable gangbang, spend it on prostitution.
Honestly, though, you'll quickly learn that prostitution isn't the way to win the game. Doing quests is. They will be infuriatingly hard in the beginning (and later in the game, too, lol, but at least you will be better prepared weapons and you personal skill wise). Don't be afraid to do quests. You will die a lot, so save often. That's just how it is. But you will earn way more XP and money.
The skeleton quest is good. Hire that Indiana Jones wannabe each time, and he will complete it for you. Use the wiki extensively, it's a fantastic source of information about the quests. I recommend doing the "look for the missing caravan" quest early too. You don't have to fight, just savescum and run (or sneak)