The only way for Vince to join you is if you shoot Danny's foot instead of Justin's.

If Wyatt stayed in the car, he will join Tavia regardless.

If he went to find the injured person, Tavia has to say that they might find friends or family in the community.

The only way for Russel to join Tavia is to say he might find friends or family in the community.

Bonnie will always join Tavia no matter her choices or what you say to her. She's a freebie.

If Shel leaves the Diner group and steals the RV, they will join Tavia regardless.
If not, the only way for them to join Tavia is to say there will be kids and adult of all ages.

Note: Becca will always follow her sister.

If you want a Perfect Run you're going to want to make sure that Shel steals the RV. Otherwise you won't be able to recruit Russel (or Wyatt if he left the car to check on the guy.)

All of the optional characters you save serve absolutely no purpose in Walking Dead Season 2. Occasionally they will show up in the background, or the camera will linger on them for a few moments to say "Hey, there's that character you rescued in 400 Days." but that's it. No real special scenes beyond that.

So, if you find yourself not saving everyone because you made a wrong choice here or there, don't worry about it. I'm not saying it won't matter in Season 3, but as of right now it doesn't serve much purpose beyond an Easter Egg.

I've had a few people contacting me and thanking me for my effort. It's appreciated, and I'm glad my guides are able to help people. I also accept trading cards, coupons, and other gifts as a form of thanks as well. ;)