Frank, what are your top 5 tips for calming a whiny baby?
Have that baby seen by a professional medical practitioner and get a proper diagnosis so you don't just think you're dealing with a cranky baby when in fact you're dealing with a juvenile leukemia case with a 100% mortality rate after 6 months.
Once you're sure the problem isn't medical, just stick to your guns. If the baby's in a mood and has been for weeks on end, and you've tried everything else, then you're right and it's all in your head. So what if your baby screams? Lots of parents get a whiny baby sometimes, it happens to all of us.
If you're a step-parent, try not to form attachments. Babies come and go, people come and go. But if you absolutely must form attachments, there's some stuff you can do: one, get a relationship with the baby's biological parent, and then try to co-parent as much as possible. Two, learn how to care for the baby on your own in case the biological parent "disappears" -- you could even get yourself a refrigerator magnet with a picture of the baby on it.
Don't try to be a mom. Moms only stick around if they want to. If you can't stay for the long haul, no big deal. Once you're sure that a whiny baby isn't actually a dying baby, you should stop feeling bad about it and just do what you gotta do.
Get counselling for the unrealistic views that you might have about babies. Don't let some boring old hippie tell you a baby is the "the whole world in miniature" or "the most sacred gift." It's a fucking human, not your saviour or whatever. They'll just make you feel worse, like you're not doing enough or something.