I've always found door to door and cold calling to be the most successful for me. More so door to door though. It gives me a chance to actually meet the person in charge as well as drop of a flyer and a few business cards. Plus, if they're a well know, reputable, company, they'll usually have some sort of "bulletin board" where others can put their business card or flyers -- that always helps too, especially the flyers with the rip off tabs...
If you go the route of creating flyers (with rip off tabs) be sure to post SEVERAL in all your local supermarkets, city/town halls, schools, restaurants, etc...
SIDE NOTE: Unless you live in the likes of Silicon Valley, it's very likely that even the highest of professionals in your area still do their own shopping, you know...
Another neat way is to look in your yellow pages and find any business without a site... Hit them up and offer them a basic design package for say $99. This is NOT what will enable you to retire early on, it's merely a feet wetter.
Get them interested, after all, most businesses, especially those who can advertise in the yellow pages, will jump at the $99 price. (If you don't seem to be too successful at that price point, bump it up to $199 or even $299)
Your retirement fund will be built by selling them on other services once the original site is finished... Maintenance, social media building or management, SEO, etc...
If you come across a site that is really despicable, visit the site owner personally and figure out a way to find out if s/he designed it themselves or had it done for them. Provided they DON'T say that they built it themselves, ask if they're happy with it. If the site is that despicable, chances are they will scoff, which just opened the door for you to promote and offer your services.
If you subscribe to your local paper, look through the press releases. Find any new businesses and contact them right away. I can almost guarantee your competitors already are, so, the sooner, the better. Also look for people posting some classified ads for events. Contact them, ask them if they'd be interested in a small website to help them promote the event. Look in the classifieds for people looking to sell high end jewelry. Ask them if they're interested in a 1 page ad (well, a one page BEAUTIFUL ad which will increase their success rate and possibly the sale price -- if they get enough interested people, it could start a bidding war). (for the small types of sites, like the jewelry pages, you may have to host it on your own site, but that's ok because its more publicity of your site and name).
Another idea, if you're in this more for the money than for the love of designing (which is fine), subscribe to a few of the higher end "website template" sites. Create a local site for your community and break it into sections for each business type. Upload the screenshots into the different sections.
When you contact businesses in your area, you can offer "Ready Made" or "3 Day Turn Around" websites for just $199 or whatever price the market will bear in your area. Then, be sure to suggestive sell other related services (such as hosting, domains, monthly maintenance, social media management, shopping cart, SEO, etc...)
I did this a while back and it was actually more lucrative than I thought it was going to be, however, I am one of those who is in it more for the love of designing, so it just wasn't for me. I sold the site to a colleague and he still does rather well.
Lastly, if you're willing to take a little risk, find some sites that really suck and design a kick-ass, out of this world, website. Be sure you include as many bells and whistles as you can. Once finished, contact the owner of the company the site is for and offer it for a decent price. If s/he says no, ask if it's the price.
If they say yes, you now have your self a GUARANTEED sale... (usually). Haggle with them a little, a lowered price is still a sale none the less...
There is a little risk with this option, but the wins usually outweigh the losses, especially since businesses are more likely to spend some money if they know the ROI is decent enough Plus, for the sites which do not sell, simply change them up and offer them to the next guy. No harm, no foul.