Did you read the .txt file that came with the game? Also, remember that you should play this game with the 3.9 player, not the 4.0 player. There are some commands that 4.0 won't understand properly. It's always best to play 3.9 games with the 3.9 player, and 4.0 games with the 4.0 player.
General
1) I don't know what to do to start the game. I can walk around the house but no girls show up!
Have you read everything in your office? You've left a note to yourself about two important phone calls you need to make...
Lorna
1) I get to her apartment, but after we have a coffee, I leave. How to I have sex with her?
Remember your phone call to Sydney Moon at the start of the game? Didn't you tell yourself to thank her about something?
Yulia
1) Can I have sex with her? I send her to the hotel, but when I move her into her apartment, nothing happens.
A hotel isn't the only option. Don't you have a spare room in your house?
2) Other players have mentioned panties and other things belonging to Yulia. Where are these items?
See above. If you send Yulia to the hotel, those items won't show up. If she stays in your spare room, they will.
3) Can I do anything with Yulia's items?
You can do some things with them, but nothing that have any bearing on winning or losing the game.
Sharday
1) I tell her that making videos is a good idea, but then she leaves. I get the impression I can do something with her. Can I?
You have a couple of turns to try things with Sharday after telling her making videos is a good idea and before she leaves. Try showing her your cock or asking her to suck your cock since she keeps dropping hints about it. You can't have a full scene with her until the pool party.
Aria
1) I've seen a partial point list that gives a point for having anal sex with Aria, yet when I try it, she won't let me do it.
Aria is very picky and private about anal sex. The only way she'll let you do it is if you know what you're doing. The only way you can find out how she likes it, is if you see how Kathryn does it to her in their lesbian encounter.
Bonus Scene
1) How do I find the bonus scene?
When Nadine leaves after you fuck her, she goes out through your office while you answer the front door. Nadine leaves a note for you somewhere in your office. The note is from Bettie Ballhaus. Where would Nadine leave a note from Bettie in your office?