For planets you do need a lot of magnification. I had a look at Mars last night on a 250P-ds, thats 1200mm focal length plus I was using a 5mm eyepiece. It was still small and looked nasty because of atmospheric conditions.
The higher the altitude of the target the less atmosphere you have to look through which helps. Also you need to have a look at your telescopes specifications to see what the maximum magnification can handle and then find a suitable eyepiece. If seeing conditions aren't good then nothing will really help you, but you can always pick another target like double stars.