Nothing like getting a conservative girl to cross her boundaries
The trick is... timing, get her horny and "accidentally" lick her ass when you go down on her, if you play your cards right and don't push her but encourage her and compliment her you'll have a proud little cocksucker in no time...
and then the next step, make her see your seed as a reward.
I truly believe that by nature any woman wants to sit on her knees in front of a man sucking his cock and be called a "good girl" for doing so. (preferably without using her hands so she truly feels like a serving sl*t)
The funny thing is that when you get conservative girls to cross their boundaries they tend to be very loyal.