Hi,
my number one tip is to use the antialiasing properties of the camera object. My own preferred setting is
oversampling pass 1 = 1x
oversampling pass 2 = 16X
Often users invest hours or days into modeling a great object and then they ruin it by rendering the image with a to low antialiasing setting. So use for your final rendering at least 1x/16x.
Bye,
Martin