What would be the most optimum approach to cleaning Dialogue from a location Recording?
One of the first things I normally do is removing clicks, tisks and different kinds of glitches, mostly by freehand redraw of the bad waveform, and removing handeling-rumble. Often there are also small distracting sounds that will need to be replaced with clean parts. As with all dialogue editing, when replacing bits and pieces it's EXTREMELY important to keep consistency, a bad jump in roomtone can ruin the illusion completely. Actually, one can use that effect creatively too (most no-nos actually can!), but for that one must REALLY know what one's doing :-) When it comes to noise-reduction, you must be very careful. If the recorder and/or the mic is very noisy then you'll have no choice, but when it comes to regular ambiance a good Expander might be a better choice than a noise-wash. It takes some experience to know when to use what and why, but it makes a big difference.
As Jay said above, there are near well an infinite numbers of things that can mess with the recording, so it's not easy to give a good single answer to this question without knowing what's wrong, or what will get wrong.
Most of the things though that can mess with an otherwise good take, not to mention those things that might bollocks it up completely, is frankly mostly something that must be taken care of on set. Though you can reduce the effects of humming blondie trafos, squeaking dollys, and loud fansystems in post, it WILL affect the sound, often quite a lot, and other things like out of focus mikeing and too much distance can't be fixed at all, only possibly slightly polished if you're lucky...
Best advice: OBSESS over the signal before recording. Of course, you don't always have time to fine-tune your placement and/or technique, but IT'S WORTH IT. Three minutes worth of adjustments pre-recording (listening to the source from several angles, eliminating any ambient interference that you can control), will save hours of editing and cleanup.
For said cleanup, I usually start with an NR plug-in (BNR, NoNoise, or even the default in Soundtrack Pro), a high pass filter (usually no less than 100hz), an additional EQ to add some clarity and/or remove high-end noise (notch filter), and then finish it up with a little gain to bring everything back up.