To state the obvious, the top spot on Google generates quite a number of leads, but my biggest suggestion is groups or online forums dedicated to something specific.
If you're a pro with PhotoShop, being involved in those forums can generate leads. Not the Adobe Forums, they're too big, find the "PhotoShop Gurus of Kansas City" or things like that. Be the big fish in the small pond
I'm involved in a number of web design forums and still have friends and clients that I pick up 20+ years ago. Also involved in a number of WordPress groups (beginner and advanced). My reason for being there is to share knowledge and help, I have lots of things in my head that I need to share with others. Constantly sharing SEO updates, news, design, programming, software updates etc with my wife drives her mad, so I share with others
At the end of the day, I'm providing help to others (news, coding, suggestions, troubleshooting) and that usually trickles over into other work - whether advanced coding, rebuilding sites, SEO etc.
I've been involved with networking groups too, and while they provide results, SEO is often a hard sell in those groups. Web Design? No problem, they understand that, but "Cold Pitching" SEO every week to 25-30 people doesn't usually translate well.
