I have a bit of time before I need to get to my shop so I will take a crack at it. for precious metals you have .... processors which come in about 40 or more types and construction styles. green fiber ,brown fiber, black fiber ceramic,with lids, without lids, with gold lid,s with 1 gold lid, tungsten based ,kovar based, copper based, aluminum based, or any combination of metals. with solder, without solder, gold /tin solder gold/silver solder lead/tin solder. with micro wires, without. Ram fingers, chips various base metals. pins all shapes and sizes all types of base metal and all kinds of yields. Cards, flatpacks, gold corners, monolithic caps,reed switches, dip switches, relays, contacts, high grade, medium grade, low grade, plated, rolled gold ,gold filled and so on.
You have to learn about the base metal for each style and type of component, how to eliminate base metals, how to recognize what you are looking at, how to test metals. Best recommendation is to read hoke, buy goldsilverpros book on ewaste recovery and refining and go to Lasersteves site to watch his videos. Samuel-a has a very fine site as well. Read many many posts.
You need to decide which material you will try to process first. Many start with ram fingers in a/p as it is about the easiest to learn and will teach you many basic things. Move on to a sulfuric stripping cell for lids and more a/p for processor bodies. Continue with ball milling for ceramics, sodium hydroxide stripping for boards as well as incineration for chips. All of these will school you in filtering methods, base metal removal, dissolving values and dropping gold and other values. Along the way you will learn silver, platinum and palladium recovery as well as how to inquart, cement, wash, dish prepration, fluxing, melt and admire your work. In my opinion, with diligence you will have a basic knowledge in about a year to a year and a half. You will never stop learning and you will make many mistakes. If you understand all of what I wrote above you are off to a good start. If you don't understand any of it.......... buy the books, read the forum.... Enjoy the ride.