Good evening. Yes, material components CAN add a boost to your spells and rituals, as they can help you harmonize with the specific vibrational essence of the planetary or celestial sphere that aligns with your intended work. However, it is not absolutely necessary, and some even say that no physical media are required to work any sort of ritual (just you and your Will alone). A good fictional example of this is the classic film, The Raven. Boris Karloff and Vincent Price have advanced magickal skills and can use Will alone to work their magick, but Peter Lorre has to use physical tools, etc to do his own. It still works, though. Just remember, what is good for the goose sometimes is not good for the gander, and experimentation will give you a better idea of what you need to do your own work. Now, regarding the physical materials. You might want to consult some published tables of correspondences; a classic is Liber 777 though there are many others, and you can no doubt find lists of materia magica online. In regards to substitutions, you need to know the nature of the herb, metal, stone, curio, etc. and how it aligns with the spell. IE: you may see that the metal gold is often listed as a base for solar talismans, yet in today's world, gold is very expensive and most who own some would have it in a safe place and not using it for a magickal artifact (at least, I wouldn't, not in my neighborhood!). However, it is generally agreed upon that you may substitute another surface, say maybe a gold-colored plate, or even yellow-gold paper (like a nice goldenrod). It might not harmonize as well with the Solar sphere but it will still get the job done (especially if you prepare the paper and link it to the Sun via ritual). Knowing the nature of the item will allow you to try and substitute another in its place (or, you can omit it to a possible decrease in the effectiveness of your work, but this is often done when working with older books that ask for inhumane or illegal acts or items in the lists of tools or actions). Maybe someone else here can add more specific details on ritual substitutions?