....Besides being at a vulnerable point in their lives....
Think about it--when you're stressed out, you want to escape. Life's mundane crap can keep anyone stressed out like student loans, or having the desire to skip a day at your boring job. What do people commonly do to escape their stress? They watch TV, listen to music. Doing this takes them to another world, one where their lives are carefree and filled with excitement.
What if you could be someone's music, or the Tv show they escape to? Some say they'd rather not, but they haven't had the pleasure of experiencing someone who'll take them out of their stressful world, and into a fun, carefree world.
It's like that one friend who's a bad influence on you, but you keep going back because every time you meet up--it's a new adventure. The feeling becomes addictive...for a while.
You catch them at a stressful time in their lives, and tell them you just want to take a load off their shoulders. When you take them out, you either take them to place that will get them out of their heads (such as a carnival), or have them thinking about a better life (that they'll later associate with you). I'll provide an example of both.
--A place that'll take them out of their minds:
do this for the types that think way too much. You'll see they take a bit longer to reply, and try to be as clever with their responses as possible, or seem filtered.. as if they can't say what they want to say. Bring your target to a place that is visually pleasing like a carnival, or even a club. I'd choose a carnival to bring out their inner child, but only if they had a pleasant childhood. Soon enough they'll fall for you, and associate pleasure with you.
I did this with all the "intellectual" types. See the first book for a specific example.
-----Having them associating you with a better life:
Your target is so stressed out, they'll feel as if they're hopeless. This is usually true for people drowning in troubles like a marriage they cannot get out of, a shitty job, etc. The reason it has to be a "mundane" problem, like a job is because you want your target to associate you with a sublime feeling. Don't tell, rather show them your life is the opposite of what they're stressed about. Your target feels like as if they can't get out of an abusive marriage? Show them you're nurturing, and considerate of their feelings. Make them promises and fulfill them, but make it so no one else can do this for them.
If you want a real relationship, I'd advise against this. Once things start becoming too real, the other person may lose interest, or they'll just run.