Hi Allan:

There are several strata in scraping. It is possible to spend a very
significant amount of money.

I would not proceed without a known reference - straight edge or surface
plate. The often on sale 10x12 surface plates from Enco would not be a bad
investment. I purchased a used DoAll surface plate, and an Enco. I had them
certified and the Enco plate needed a bit of touching up to get back to
grade 'B' - this after I used it for a poor man's surface grinder ala Guy
Lautard's book. Even at that, grade 'B' surface plates are tight enough for
scraping.

Cast iron is far easier to scrape than steel. That's what I would practice
on.

Prussian blue works pretty good. I would add a rubber brayer to the tool
list.

Enco makes an Anderson Bros' tubular scraper handle clone. They have
replacable HSS inserts. HSS does require fairly constant maintenance, but
carbide & the ability to grind it can be pretty spendy.

Books are good for some, but seeing the scraping action was an eye-opener.
Just watching it happen made things easier to understand.

Having a reference on scraping, reading the spots and possibly more
importantly, how to detect when you're not making progress, all help.

Scraping is addictive.