I work with a comparatively small number of clients who may come from most English regions so it's hard to generate the necessary "critical mass" to make networking work really well for me.
That said, my best single source of clients is through referrals. The best
client advocate I've had to date encouraged his 2 siblings, an in-law and 3 friends to see me

! Some of the advantages of referrals are that the prospective customer already knows what you offer, has decided they want it and has thought about when might suit them best to have an appointment ... so it's an amazingly quick and easy process for both sides.
I feel
consistent SEO and PR would work wonderfully for my business but you've got to put in sufficient commitment over the long term to get the most benefit from them and I haven't done that.