I am a tradie, so I can speak from some (little - 23 years) experience.
I have found most (about 90%) of our customers come from word of mouth and repeat business.
Look after your customers and they will look after you.
Now please remember this is my opinion only, but I have found advertising ( which failed dismally for us the couple of times we tried it!!!) gets us lousy customers only after rock bottom price.
It usually attracts those who are quote shopping. This usually spells grief.
I hear all too often people complaining about tradies, but let me tell you with a sincere heart, that customers can be a royal pain in the little donkey.
I now choose my customers rather than the other way around.
If your good, I'll work for you, but if you are just price gouging and whinging, I can recommend some great tradies....
A good customer base is worth a lot and once established work hard to keep it.
Trust is the key element.
As far as getting new customers, I have no problem in asking any of my customers for referrals and recommendations.
They are always happy to oblige as not only do they feel a mutual respect and bond, but they also get the feel good gratification and knowledge that you will remember them.
Its a win - win.
Good luck with it all
Brian