It wasn't until last year that I really clued on to the fact that different fibres had different properties and you had to find the right project to take advantage of those properties, and not be hindered by it.
For example, all of my amigurumi projects are made with acrylic. Initially this was due to the colour and price factor, but I later learned that acrylic doesn't have a lot of elasticity - the yarn itself doesn't really stretch - which is what you want with amigurumi, so it keep its shape.
|Mr Minion here is made of acrylic yarn. If I'd chosen a different fibre, he might not have held his shape so well. The pattern can be found here|
|I made this hat using an acrylic yarn. While it was the colour and weight (and price!) I wanted, it didn't work out too well for the hat. It has no stretch in the body so when I tried to block it, I didn't get the outcome I wanted. It isn't all bad, but I think I will make it again using wool. Find the pattern here|