What part are you actually having trouble with? I actually have been playing this for the past 4 hours, so I actually finally have a handle on it.
Warning, Wall of Text incoming: Here's a quick reference for if you forget (Or skip past tutorials because you're too busy fapping)
Basics:
Excitement is the green bar on the right. The higher it is, the slower it drains, so keep it higher if you need it to last longer. This is also what brings the customer closer to cumming. Something to keep in mind, is the energy used to keep excitement high on one enemy does not carry over to excitement on the next, so use only as much energy as you can get away with. This will come with practice.
Cum meter is the white bar on the bottom of the enemy, and is mostly self explanatory, but one thing to keep in mind is that swapping to another enemy lowers the first one's excitement, but not the cum meter.
Energy is the meter at the top left of the character's card. The worse they are at an activity (and the higher the level enemy), the more energy it takes to keep using the character to do it. Try matching the character that's good at a thing with the thing they're good at. Go-figure.
Ultimate abilities are on the second from the bottom of the card, and fill up blue as a character is used. the button will appear as a green "Ultimate" button on the right. When the ultimate ability is activated, the blue will turn yellow on most and start draining to tell you how long it lasts. The only exception I've run into is Queen, as hers is drained completely on use.
Experience is also mostly self explanatory, but the bar is in orange on the very bottom of the character card
Enemy types are shown on the left and by the color of the card. each type has a unique effect, pay attention to them. These are actually mentioned in-game, READ THE DESCRIPTIONS.
Enemy preferences are shown at the top of the enemy's card with an image. They are completely self-explanatory, no need to explain a picture of boobs or an ass.
At the far right of the top row, you can see how many enemies are left in the fight, assuming it's longer than the window you're given (Which does happen)
Intermediate:
Queen is used as a well-rounded (pun only partially intended) character that has an ultimate that refills 1 energy for every girl in the roster (Including herself).
Suki is a specialized girl with small tits and ass, but is damn good at blowjobs and vaginal. Her ultimate keeps the excitement meter from draining as fast.
Esxea is not quite the opposite of suki, but not far from it. She's better at tits and ass-play, but isn't bad at the other 2. Decently well rounded as well. Her ultimate makes it so she doesn't lose ANY energy filling the excitement meter for as long as her ultimate is active. You can abuse the hell out of this in the fight where you get her, DO SO.
Scarlett is a highly specialized girl in 1 area, her tits. She is lacking in 2 others, her blowjobs and pussy are below par. She is entirely devoid of ass-play, pray you never need to use her for it. Her ultimate makes the cum meter fill faster.
Helpful tip: When you get to mudders, the mud is a stacking debuff making the cum meter fill slower that goes away with time. The more stacks there are, the longer it takes to dissipate. Don't try to force plays through the mud. Push a little, wait for it to go away, then keep going.
Helpful tip 2: If you're getting overwhelmed by the higher level enemies, take those out first, then use the lower level ones to regain energy, as they can often times be taken out with less energy than you gain back. Use the lower level ones almost as a reserve of energy to keep yourself going longer.
Hope this helps anyone else that reads this, I know I skipped past the tutorial and had to figure this shit out the hard way. Good luck, and happy fapping.