Prepare your royal icing, following the directions in your chosen recipe.
Take out about ⅕-1/4 of your royal icing. This will be your white, for the spider webs.
Tint your remaining royal icing. You can do it all the same colour, or divide it into little bowls to tint different colours. I like to do a mix of orange, green, purple, and black,
Check the consistency of your icing AFTER tinting. When you use a spoon to pick some of the frosting up and drop it back down into the bowl, you’ll want it to smooth out in between 5-10 seconds. (I like to keep it about 6-7 seconds)
If your icing smooths out and disappears in less than 5 seconds, it’s too runny. Stir a little more powdered sugar in, until it is in the 5-10 second range.
If your dropped icing takes more than 10 seconds to disappear back into the rest of it, it’s too thick. Add a little water - a few drops at a time - and stir well. Re test, and adjust more as needed.
Once your icing is all the proper consistency, transfer it to frosting bags.
For me, I’ll put the colours into bags just as-is. You can use a coupler and round tip if you’d like, I don’t find it worth the hassle. Squeeze any air pockets out the back end, tie off the bag close to the frosting, and do not cut the tip off til you’re ready to use it.
For the white frosting, I’ll set the frosting bag up with a coupler inside, trim the end, and affix a smallish round tip - usually about a #3. You want it small enough to be relatively dainty, but wide enough that it leaves a thick enough pipe of white frosting to pull out well. Squeeze out air pockets and tie off the bag.
Cover any frosting not being used, it dries out quickly!