The viewfinder is cleaned like a lens. The screen and mirror, you do not clean. Use a blower for dust if you must.
Thanks! I got the camera used and saw some fingerprints on the focusing screen... wondering what's the best way to clean it (without sending it to service obviously)
If you must, you can try alcohol and soft wipes of q-tips.
Trying to clean a focusing screen usually leads to frustration. If you must, you can try alcohol and soft wipes of q-tips. The better solution is simply to exchange the screen, they are not that expensive (about 100$ used).