As a general rule: render as large as you can in FE using 4-point AA - to get rid of as much jaggedness as possible - then save the reult as a BMP file to retain the full amount of data in the picture. Open the picture in your favorite graphics program and there resize it to whatever size you wish - this will give you additional "anti-jaggedness". If your render-size is reasonably big then you can even raise the resolution (dpi) to f.ex. 200 or 300 while downsizing, for better reults when printing - if that's something you do. Finally, in your graphics program, use the sharpening tool to enhance the features of the picture. Then save it as .jpg (don't go below 85-90% quality for jpgs...) or .bmp, depending on what you want to do with it.

 By "large" I mean really large. If you want your end product in the order of f.ex. 800 x 600, then you should render it first at a size of at least 3,200 x 2,400 pixels or bigger. This will of course increase the render time considerably since the render-process in FE makes calculations for each individual pixel in the picture. Find a good balance between size and render-time. 

 The render process can be done in the background using the batch-render option. It'll take a little longer this way, but if f.ex. you are using a system with more than 1 processor core then you will be able to use the machine for other purposes while the batch-processing is going on.