Hi Dave,
Just like you I have a 10" newt so I possibly can understand some of your position. Please don't think of me being presumptious with my post as i'm just not sure of your experience.
Firstly I would agree with everyone that you need a steady atmosphere for good seeing in relation to Mars and for mostly anything else. If the conditions are average then Mars will not look like much more than a red round ball.
A rough guide I use for how good seeing is first - any twinkling in the stars. If they sparkle like a diamond then there is something going on in the atmosphere and therefore the viewing may not be so good. You can get a better idea of your night sky by looking on
www.skippysky.com.au/Australia
or something similar. Transperancy has to do with the amount of cloud in your area and seeing is related to the atmosphere, the darker the blue the better.
Secondly your mirror cooling down and tube currents, if you have a solid tube, can really affect your seeing and you might have noticed that already. The best time I have found to view planets is just on dusk when the stars start to appear. Or later on when the scope has sufficiently cooled down.
And lastly if you are using the 10mm eyepiece that came with your scope then you are already a step behind. While the 25mm is ok the 10mm that came with your scope is pretty much something you should think about replacing if you want better planetary views. You will notice the difference with a better eyepiece.
On the good side if you can get the great seeing conditions, a good eyepiece and your scope cooled you will get a pretty good view of Mars. About a month back I viewed Mars at a dark sky site with very good seeing condtions and could easily see the polar caps and a dark lane with detail that ran from top to bottom so don't worry.
Good luck with it.
simmo
