Hawkesy
My top tip would be never own your own turbine aircraft, no experience of piston, but if you can lease one from an owner then by far the best way.
Having had 6 years experience of running a well known 355 F1 on the charter market, it is a complete lottery on what is going to go wrong next. We had everything from engine gearbox making metal, starflex not running to time, blades delaminating, heavy landing whilst on lease, numerous autopilot problems and finally almost the improbability of a thomas coupling failure. We were lucky as we maintained our own aircraft but over the six years almost certainly paid Mac's over £350,000 in parts and various engine overhaul shops the same.
Saying all that we averaged 275 hours a year charter at a self drive rate of around £ 550 dry, but as mentioned we did our own maintenance which was 'lost' in the parent organisation. This made it look reasonable but if contracting the maintenance out would have been a totally different story.
During my time in the industry the 'ideal' way to run this type of business is start a training school where your clients love the idea of owning an aircraft, they buy one, you lease it off them and charter, then maintain it as well. Several well known helicopter businesses started this way.
The only way to make charter work is to lease an aircraft off an owner who wants some revenue to a) make it a business and claim the VAT back and b) subsidise the cost of ownership. Many ask can they make money from this, the answer is always no, based on turbine aircraft.
If you bought a new aircraft with tip to tail power by the hour then you can accurately forecast your costs for years to come. However the interest and depreciation costs on a new aircraft would wipe out any profits from a charter operation.
After saying all this I admire your ambition, something I would like to do sometime soon, and don't forget there are many successful operators out there today. If you have the bug then very difficult to do anything else. Just be wary and if thinking of a turbine then find someone who owns one and lease it !!
Hope this helps and obviously just my opinion from my experience operating what a a well known Chief Pilot calls the 'Plastic Pig'
Regards
F09