Best way to gain more clients?

In my personal opinion I believe there are many avenues you can explore to gain more customers like ads, business cards, seo, etc. however; in my own experience as a contractor I've come to find if you go above and beyond to make customers happy or at the very least, leave a good impression, word of mouth can become very powerful. When I was in my first year I went crazy with a website, business cards and any social site I could get my name into but most of my clients come from referrals. Hope this helps, I do still think a little bit of everything helps but this is my experience.