First things first: the title has to be BIG and easy to read.
The design has to be seductive, but not too provocative. A woman or a woman's body part can hint at sedution, but with full nudity it's gross. There's a thin line that can't be trepassed - or the cover will look vulgar.
The book is mainly a guide (with stories here and there), so it has to communicate reliability.
Let's make the reader imagine himself having success with women. Let's make him desire it. And let's make him wonder what's inside the book.
I suggest taking one of 2 directions: either use a woman image (feel free to be creative) or a couple.
It's necessary that it's eye-catching and attention-grabbing.
Feel free to experiment with colors... but keep in mind that I may ask you to change them if I think that a different color scheme may work better.
The book is in Italian, so you'll find italian texts for this job: please copy and paste them as they are.
The size of the book is 20cm x 14cm (20cm is the height, 14cm is the length). The side should be around 1,5cm – 2,0cm (I can't say this for sure yet, so it's better if you can design an adaptable side).