Somehow, word of mouth never worked for me. I only ever got one repeat customer (he was really really good first time, but second time, mediocre), and one customer through a referral (very good, but just once). Out of 170+ over 25 years.
I see the reason: my customers are people who don't know anyone they could possibly recommend me to, because they are from random industries and random places. Also their projects are one-off: usually first and last software projects of theirs, ever. Working for someone with large networks who can make referrals means losing money because these people also know good coders and can hire well. I never solved this and rely on outbound all my life.
Do you know those customers personally?
Word of mouth mostly comes from repeat customers as well.