A nice, and simple quicktip today: Pressing the F9 shortcut key will perform a re-render using the previously used camera and output settings. This will also automatically overwrite the file if a save file name has already been used. This is certainly one of the most used short-cut keys in 3ds Max.
As all of my other postings normally come with an image, I felt I needed to include one with this, so here goes:
When performing render using mental ray, don't forget to get in the habit of always enabling the "Geometry" option in the VFB's 'Reuse' box. (After reading my other posts, you should now know what VFB means.) This will cache the geometry to a temporary location on your hard-drive ensuring the 'translation' time of converting the geometry to something that mental ray understands, is kept to an absolute minimum. In some cases, the translation time can often take longer than the physical rendering phase.