Baby cries during sleep routine

Hi I am new to this group and I have a daughter who is 3 months and 3 weeks. She sleeps well through the night, once she falls asleep. And she usually takes 3–4 naps a day. But getting her to sleep is a struggle! She has been crying every time. As advised in many places, I’ve set a routine but it seems like maybe she has caught on to what is going on and starts crying knowing it’s time for sleep. What can I do to lessen the crying, and to eventually have her go to sleep on her own? I’m open to any resources like books, podcasts, etc that might help.