Getting Baby to Sleep in Crib

I've been bed sharing some times in the nights and letting her sleep in her rocker thing because she just won't sleep in her crib. She's 3 months now and I've tried quite a few times to get her to sleep in her crib and she just won't sleep and starts screaming so I just break down and let her sleep the way she likes. She's starting to move around a lot more and she's starting to get where she can roll on her sides and I want to get her to sleep in her crib because I worry she might roll herself out of bed or get in a bad position in her rocker does anyone have any tips for getting her to sleep in her crib?

I know everyone has different opinions about bed sharing so please don't leave negative thoughts on it.. it's what I felt comfortable with and one of the only ways she would sleep.