Pressing the SHOOT button gives you access to the Markers tab. Here you can upgrade your studio, and start to shoot a new scene. On the top part of the screen, you can see the minimum requirements for that specific scene.

There are 3 markers on the screen: Happiness, Lust, and Attraction. To raise each marker you need Energy.

For example, if you need to increase your Lust, click on the Lust button, and after that click on the Arouse button at the top of the screen.

On the upper part of the Lust Window, you can see your character XP, Star XP, your Lust level, and the available Energy.

In the center of the screen, you have access to the various gifts that can be used to increase your Lust level. For example, if you select the plain Dildo you will consume 20 Energy and get +40 Lust. If you select the Vibrating Shell you need to pay 4000 Cash and consume 20 Energy and you will get 250 Lust and 75 Character XP. If you use the Vibrator you will get 300 Lust (1), 5% XP boost (2), and 100 Character XP (3). There is no need for Energy consumption if you pick a gift that requires Diamonds.