How do you teach your baby self soothing skills?

My Little is 3.5 months and won’t go to sleep without being held, rocked it booty pats. (She’ll scream her head off until someone picks her up and then she’s wide awake so I don’t like leaving her too long) As much as I love baby snuggles sometimes I need space/to get work done.

The baby sleep world always talks about how important it is to teach you baby to self sooth, but that’s it. No one says how… what are some steps to teach your baby to self sooth even if they might not be ready for sleep training yet?