Tailors or anyone looking to gather plenty of cloth salvage items will already be focusing on many the creatures that drop totems. Since each type listed will have an influence in different regions or maps in the game, availability will be dependent upon where you are leveling at the time. As a general rule, bandits will be found in maps with a heavier human and sylvari influence, inquest in asuran areas, and Sons of Svanir can be found throughout the Shiverpeaks.
Many of the creatures that drop venom sacs will also drop other fine crafting materials, so you can often maximize your time by gathering two types within the same area on a map. For example, trolls (commonly found in caves) can drop venom sacs, bones, and vials of blood, so can be a great option. Grubs (also mostly found in caves) can be another solid source for venom sacs and can also drop fangs.
Drakes, harpies, and raptors will be your best source for claws depending on which region you’re in, with Flame Legion tending to be an excellent source for Large Claws at higher levels in the area around the Citadel of Flame dungeon. Drakes in particular tend to populate most maps, and will be found along rivers or other bodies of water. Drakes can also drop scales, so tend to be one of your better options.
Of all the fine crafting materials, piles of dust tend to drop the most commonly. This is partially due to the fact that you’ll end up using larger quantities for crafting discoveries, or in the case of jewelers you’ll be using dust to transmute gems into the next higher tier version.
In terms of creature types that drop piles of dust, elementals and risen have proven to be the most reliable sources, and are found throughout most of the higher level maps. For jewelers, you’ll want to be focusing on elementals either way since different types of elemental will drop specific types of gem.
Grubs can be a great source for fangs, and will be found in various caves on many of the maps. They’re also a source of venom sacs so can be well worth the time to seek them out even though you may need to work a little harder to reach them. An alternative would be skelk which are found in more swamp-like environments, but just like grubs they can drop both fangs and venom sacs making them worth seeking out.
Finally, if you’re also looking to gather leather to make armor and weapons, boars (and to a lesser degree, wolves) are somewhat common creatures found in low or mid-level maps and can drop leather salvage items with roughly the same frequency as fangs.
You’ll be spending plenty of quality time in or around water if you plan on collecting many scales. The good news is that most creature types found in those environments tend to drop scales somewhat commonly, so you have a bit more flexibility in terms of which creatures you decide to focus on. Skritt are a bit of an anomaly here in that they’re more of a subterranean creature rather than amphibious or aquatic. You’ll also run into them far less frequently than the other creature types listed.