CLK,
I managed to move from instructing to charter 7 months ago. At the time I had 850 total time with 150 twin. I had been doing some parachute dropping in an Islander but the majority of my time was instructional.
I have experienced the kind of reception that others here speak of. Many operators don't regard instructional time too highly. I guess that is from their previous experience and you have very little hope of persuading them to change their mind (I don't think I would try).
I have flown a few co-pilot hours with my new company and some of the approaches that the 'experienced' guys fly are appauling. Most of the strips we fly into are at least 2 kilometres long and fully sealed. We share the circuit with 737's and 146's. Despite this, these guys fly a banana shaped approach by dropping the nose, getting frightfully low and then dumping the thing on the runway lights at the approach end (we fly chieftains). These guys have many many charter hours but no instructional time.
I am not suggesting that all instructors fly perfect approaches, but I feel that instructional experience polishes up your flying skills greatly. I don't think these guys have flown constant approaches since their CPL tests.
It sounds very cliched, but you simply have to keep at it. I moved from single engine PPL/CPL instruction to multi IFR charter whilst living interstate. I knew no one within the company and simply managed to ring them at the right time. One of their employees was waiting for a Qantas start date and so I was in luck.
Another point that I think is very important is that you must realise that when you ring to speak to the Chief Pilot or owner, it will be completely obvious to the person on the other end that you are after a job. Whatever you do, don't act cagey, be honest. Tell them who you are, what experience you have and ask whether or not you may send a resume up for their file. Don't expect any miracles during the first phone call.
Assuming you send a resume, give them a couple of weeks before ringing to check they received it in the post. Don't be pushy and try not to take up much of their time. They are usually very busy and won't want to have a long drawn out conversation. We never put the Chief Pilot on the phone whether she is there or not. Furthermore, if our CP answers the phone, she won't tell you who she is. The moral of the story? Be careful, you don't know who you are speaking to.
One last point that is a pet hate of mine. Attention to detail. Take some time to ask who the CV should be addressed to. Confirm the spelling of names etc. Confirm the address. I have a killer surname and it rubs me up the wrong way when someone doesn't take the time to spell it correctly. One of the resumes we received recently was addressed to the "Flight Operations Department". We are a charter organisation!! You can imagine where this resume ended up.
Best of luck, it can be done!