The above is some good advice and somewhat more positive than mine.
A few observations: being busy does not mean you are making money, a busy fool and all that.
It may depend on your area, ours London is saturated and maybe why the prices are continually being driven downwards. A niche market like the above maybe a good idea plus in a less crowded marketplace.
I agree with the leafleting, we used to do this and it used to work but everyone uses the net nowadays.
Agree with the website, all our sales for more than the last 10 years have come through the site, but everyone else is doing this so you are not going to be the only one out there - differentiating yourself from others is difficult, but as the above says it's all your going to have so it is worth spending a lot of time on this. I use both nowadays, a straight older html site (a bit faster to load) and a wordpress site (you can use cdn to speed things up a bit). If you are starting out and dont know anything about coding/seo I would suggest the wordpress site route and use plugins (bit more bloated but easier at first).
With respect, getting a niche site to rank high is not too difficult (hat's off to the above poster though) - it's different thing altogether to try to rank highly on google for say the following keywords - cleaning companies or office cleaning. Anyhow if you are looking to rank on google - its all changed from back in the day, different viewers see different rankings depending on search history - still worth the effort. Bing and yahoo are easier - see here
http://www.bing.com/search?q=cleaning companies&go=&qs=n&form=QBLH&filt=all&pq=cleaning companies&sc=8-18&sp=-1&sk=&cvid=78d74f84a72d4809b6a818969fea7889 - being ranked 3/4 on 1st page counts for a not a great deal - unfortunately google is where its at, and as I say thats all changed.
66% conversion rates are
extremely high and I would not expect anything like that - we are lucking if we get near 10% - btw the above poster's link needs fixing on his profile page.
If I were to offer some more upbeat advice (nothing so freely given and all of that) - I would suggest trying to get a few decent sized contracts that
you can make a living from. With you doing all the work running a few nice sized jobs.
The pluses - no employment hassle (this is a
big deal), you know the work will be done correctly, low overheads so more chance of winning work.
Negatives - no holiday, all you, having your eggs all in one basket.
You could probably make an ok living from this but your not going to be living like a rock star but then you probably already knew that. Getting to the next level seems much more difficult nowadays and with some perspective I'm not sure it's worth it - t/over is vanity etc, but possibly you could get the pareto effect to work for you in reverse if you keep it nimble & tight.
Good luck