Dropping leaflets is a scattergun approach and the response rate is going to be down to the numbers you drop off.
You can for the wearing out leather way for another approach.
I used to go around all our target areas - industrial estates for example, take a sales letter / info brochure with a plain envelope - go into the reception, ask them who would be responsible for the cleaning and would be ok to drop some information off for them.
Then make sure you write out the contact's name on the envelope and hope the receptionist doesn't bin it after you left and passes its on. The next and most important part is to ask the receptionist for a compliment slip. Most times the receptionist or equivalent will give you this.
You now have the contact's name and details responsible for the cleaning, often times you will get more information from the initial contact (when the contract is due for renewal / are they happy with their current cleaners etc)
Now you need to collect as many of these as you can, get back and then get on the phone and try and introduce yourself and get through to the contact. You do have an advantage of plain cold calling, as hopefully the receptionist will remember you, you have dropped off a hand written envelop and showed some initiative (you'd be surprised at how many business owners see this as a huge plus - we've all been there after all.)
Good luck
