Getting cards in takeouts, shops, post office etc works well, people are browsing/standing in a queue...captive audience.. Always be polite, even when out and about...people remember your face surprisingly often, offer to clean up (though its surprising how many people tell you not to bother and they will get it once your gone)
Never let someone shortchange you on the bill and "put a cheque in the post for the difference" often the cheque never turns up...had that once..
Subbing can work well, just be wary of some companies...I got asked to sub for one company, did a quick google and found they owed quite a lot of people money for services rendered....
I have an ad with Yell, that I'm considering expanding the area of as its making some half decent returns.
Also make sure your listed in Thomson local, 118s, etc
Be wary of Scousers touting - Police Welfare magazine (what force am I covered by tends to throw them, thats funny the local community police officer never mentioned this but did mention scams like yours also gets the message through), crime prevention monthly, disabled childrens network, fire prevention yearly as they are ALL scams...
It takes time mate, lots of time, get comfy footwear, if you are half decent with design progs, make something up, or get someone to do one for you...buy heavy weight glossy paper and print 4 to a page...perfect fridge sized postcards that look tidy and people hang onto...might not get an immediate return but its surprising how often you will get a call 5 or 6 weeks down the line when something needs done or the lights go out etc.
If your half decent at other trades - put down odd jobs done or similar, also if you know other trades or can arrange them put down "all trades supplied" (just make sure your PL covers you for sub contractors...)