Recently had an MFF (I'm MtF) and thought I'd share some advice for any couple curious of trying to involve a transgirl. So in no particular order...

-communicate! know what she is/isn't ok doing. some MtF use their dicks, others don't. some have trouble keeping it up, but that's normal for those who don't exercise it as frequently as they did pre-hormones. some MtF are sterile btw, but always ask.

-lube! if she's going to be penetrated, use lots of it. she might be tense at first or nervous (many are scared of being naked b/c they feel vulnerable), but that's normal. gone at the right speed/depth though feels awesome, and make sure to communicate. it might sound/feel like she's hurting, but sometimes it's confused with a new type of pleasure for her

-cleaning! make sure to clean well. i had more time with him, and he did a great job. it actually made blowing him extremely enjoyable - did not realize how incredible it tasted. condoms are good for him keeping clean during anal since douching/showering isn't always 100% effective, and always be open about any STIs

-shaving! some like little or no hair on themselves or partners, so talk about it beforehand. mostly hairless dicks are a lot easier to put in one's mouth btw (but some girls like hairy/grizzly guys!)

-tongue! kiss with lots of tongue, frequently gets her in the mood. ask if she wants it anywhere elsw before diving in

-breasts! MtF often like showing/using their breasts bc it reinforces their femininity. show them some attention, it's satisfying in an unusual but very desireable way

-cuddling! snuggling before sex is a nice way to warm her up, and she'll probably like feeling close to you both once everything's done. hugging/kissing is also appreciated

-morning after! give each other a text just to be courteous/see how she's doing. even if she doesn't always seem like it, it makes her feel like you care about her

If anyone has any questions, go wild. I'm super open so now's your chance! Basically, just remember: communication and lube are your friends!