As somebody without a guru , which sadhnas can I do for devi?

I equally resonate with krishna , maa durga and maa kali as well ... For krishna ji I have been doing hare krishna mantra daily .. so I was wondering if there are some basic sadhnas that non initiated people can do for devi ? People say naam jaap but which naam ? Like should we just say "kali kali " and " durga durga" or is there any particular mantra as such