Crafting with multiple colors

Dear users, dear authors,
when you want to do multicolored needlework, what problems often arise? This question applies to all types of needlework, as I don’t want to limit it to just one type. 

It’s probably easiest with embroidery, since you can work through one color after another.
Knitting gets a bit more complicated—I used to make a lot of sweaters with knitted-in designs, which always resulted in tangled yarn or dropped stitches. I also found it harder to ensure there weren’t any holes where the colors changed.
Now, with the temperature blanket, it’s simple again—it’s just individual strips, so at most there are a few extra ends to weave in.
It’s much easier with crocheting; you don’t drop as many stitches, so you just have to keep the skeins of yarn separate.
Something I haven’t tried yet but have definitely planned to try is tapestry crochet—I’m very interested in that.

When tapestry crocheting, it’s important to keep the tension of the yarn nice and even: not too tight, so the piece doesn’t shrink, and not too loose, so you can’t see the yarn being worked around.
This also applies when knitting with multiple colors.  Here, the tension threads on the back shouldn’t be too long.

When crocheting in two colors in the round, you can always see the color transition a little bit. There are various techniques to make it as inconspicuous as possible.