Clementine is a neutral core set dude that will find a welcoming home in nearly any outfit. But she's got 0 bullets and can't hit the broadside of a barn! Why would you want to put her in your starting gang?
Pros:
Affordable Value: Her 3 starting cost and 0 upkeep makes her at the very least a cheap body to make callouts, catch bullets, and pistol whip when you're in a shootout. Even though she's 0 bullets she can still give 1 draw bullet as long as she isn't the lead shooter! Most importantly she gives you 1 precious Influence which can take control of enemy deeds and keep you from losing. You can always use her take control of the opponent's deeds while your big guns watch her back from town square!
AMAZING trait: Being able to ignore callouts from the likes of Clyde Owens, a wanted Sanford Taylor, or any other mook looking to start trouble in her saloons is insanely good. What makes it AMAZING is that she gets another +1 influence while serving drinks at a saloon. That puts her on par with the absurdly good value Irving Patterson provides in terms on influence gained per GR paid and who wouldn't want to include him in every outfit if they could?
Tips for use:
Stay out of range of Shotgun and Soul Blast. With her Ace value, those cards are like Clementine kryptonite and WILL disintegrate her with nary an effort by the opponent.
Park her in a saloon you own ASAP This should go without saying, Clementine doubles her starting influence by plopping her in a saloon you own. Which means you should be including them in your deck if want to maximize your investment in her! Saloons are also the safest place for her by far; even safer than home in many cases. The only thing that can kill her once she's dug into a saloon are cards like Kidnappin'/Ambush.
Use high production saloons: Most folks won't be willing to drop 3 influence to wrest control of a saloon away from Clementine so any saloon she's stationed at is all but guaranteed income. As such you might as well put her in high-yield saloons like Pearly's Palace and The Union Casino. They not only generate 3 GR a turn the opponent can't easily take away from you but they also offer insanely powerful abilities to boot!