Non-specifically, how do you plan a restoration?
 

Kind of relates to my thread about QTGMC making some black marks worse, but what's the best way to go about tackling a restoration? A lot of this forum is examples and solving specific problems, but I'm thinking more broadly than that: how do you go about analysing a tape to see what steps are required, or what flaws are present? What's the best order in which to tackle things? What do you look at to identify errors?

That's a pretty crappy outdated guide. Some of the guides here have gotten stale, not updated since 2011 (due to my health), but it's not anywhere close to that.

(Note: I'm currently working to fix those, add many more, and add new site features.)

It takes experience and knowledge.

When I get a tape, the first order of business is to see how well the audio and video play/capture. Any problems seen, that can't be fixed in hardware (including doing something as extreme as realigning hardware for a tape), must be fixed in software. Those are usually VERY specific to a problem, not really generalized.

My/our hardware is more advanced than others. Altogether, I have probably (at least) 50 devices available that I can use: lots of VCRs, proc amps, DVD reocrders, detailers, special capture cards, etc. Each was acquired for a specific reason. My personal stack alone has about a dozen toys in it. Hardware plays a big part in capture and restoration. (Note that this doesn't even count the excess hardware I have for sale in the Marketplace.)

Now, there's only so many kinds of odd errors you can come across. After years, you gather a library of Avisynth scripts, VirtualDub setting, Sound Forge custom filters, and knowledge for using things like Mercalli, Premiere, etc. There's a lot of tools, and preference can sometimes decide what you use (for example: my preference in Premiere for color work, though I may adopt DaVinci more).

Once capture is done, with VHS as source, it's typical errors:
- audio hiss/hum/buzz/fuzz/etc
- chroma alignment, noise -- my pet peeve of noises
- grain/dirt/etc
- color
- overscan; tracking masking if overlay bad

You also have a lot of inherent camera issues:
- ghosting
- IRE, gamma, color

Sometimes there are trade-offs with hardware choices:
- posterization
- jitter

And embedded nth gen issues:
- embedded tracking noise
- timing/timebase issues

The order of things fully depends on the combination of present errors, which is why the forum is very instance-based. You won't be able to avoid it.