Hi
I have a child that if left to scream or cry it out she would go forever... I'm a firm believer that a baby should learn to go to sleep in their own bed but that's just my philosophy... plus I like to be able to have my evenings with my DH and take off my "mumma hat".
Here's what worked for me: PS I DON'T KNOW HER AGE...
When Abbie (my dd) was around 2wks old I started to wrap/swaddle her before going to bed. I put her down and if she cried I went in and went Ssshhhhhh (a lot I might add) and rocked her bassinet with my hand gently resting on her chest... this will help settle them and help them go to sleep in their bed.
When Abbie got older around 2 months I began leaving her to cry. I started leaving her for 3 minutes. When I went back in I had no expression on my face and I just went sssshhhhh... I extended the 3 mins to 5 mins... then out to 10 minutes if she was settling down.... if your baby is still crying badly you may have to get her up and give a gentle burping/winding session because crying can give them wind... put her straight back down without talking, no smiling and leave the room. When DH was there we would take turns in going in so it was less stressful... remember NO SMILING, it provides them with a pay off for crying... you only want to let her know you are still there.
Abbie learned really quickly that mum wasn't going to give her smiles and play because its bed time. Its REALLY hard not to give a facial response but it really does work....
Good luck...
Oh, by the way Abbie has a dummy/pacifier which helps her relax from day one she has been a baby that soothes herself by sucking, it used to be my little finger tip but I decided that I needed to have my finger back and a pacifier was far more sterile. She never managed to find her thumb to suck and now when she puts her thumb in her mouth at 4 months she doesn't think to suck it...