This is from the gamerenders forum:
"Okay...
When you cut a picture, zoom in around 500 %, as long as the picture is pretty clear, and try to cut in circles, little pieces at a time. Its all about patience, your final result: a great render. Now since ur gonna save it as jpeg, set a background to a color that is not on the picture that you are cutting out. To make the background, make a layer underneath the layer of the picture.
Never use the automatic tool... The only good time to use it , is if the render is already cutout, and the background is diffrent from the picture... If you use this tool, don't ask to rate ur render, cuz it's gonna suck...
Try not to render bad quality pictures... Nobody likes them, nobody uses them...(except for noobs) We're in 2004...
When Cutting out cars try to leave the black pieces by the tires, the shadows. Because the tires look kinda stupid when u cut them around... and the only way to fix that by another person whos using your render is using the brush tool....
Now theres another way i use to render pictures, but not for others for myself... Like if i make a sig and the picture is already resized and put into a sig, but it has a bg that u dont want, then add a blending mask( or whatever its called) take the BLACK brush, zoom in and brush around the piece that u want to stay. After u have pretty thich line around it, cut out the rest using the lasso tool. But this is not for doing renders, only for personal use.
Don't be lazy and use this little guide to make a perfect render...
If someone could make this sticky since its really useful in this particular forum, that would be nice.... This will be updated when i think of something else."