Some of the key points with Riley -
Day 8, tell her the truth about why you took the job. If you don't, you get a second opportunity on Day 9.
Day 9, come clean with her if you didn't on Day 8. If you don't, you can't start the relationship. (I think this is the day she gives you her phone number)
Day 11, you need to call Riley if you want to release the video footage you have of Brody. Accept her invitation to come over or the relationship opportunity ends.
Day 20, check your laptop for a message from her. Then call her in the evening.
Day 34, go with Liza to the mall. There will be a commotion caused by Brody. Riley will duck into the Sex Shop to escape. Follow her. That leads to sex with the shop keeper.