Useful items to own

This is a list of some of the things you might want to invest in when you start out crocheting for the first time. Most of my patterns use only these things and things you might find around the house, and whilst this pattern is specific to the patterns I create, it will also be relevant to many other crochet patterns you may come across.

Essential items
These are things you will need for pretty much every pattern you come across.

1. crochet hooks. Unsurprisingly the most important thing you need will be a set of crochet hooks. Its a good idea to have a wide range, but the exact sizes will depend largely on what you are making. I own two types of hook sets - one ranging from 2mm-8mm, and the other ranging from 0.5mm - 2.5mm. The 2mm-8mm set is good if you're a beginner, but I use the smaller set far more in my patterns (I very rarely use hooks above 3mm). The smaller set I own can be bought here. Its also worth inventing in some slightly higher-quality versions of the hooks you use most often, since this will make crocheting for long periods more comfortable. For my patterns the most used hooks are 2mm and 2.5mm.
2. Yarn. There are a wide variety of different yarn weights and fibres, but most of what I use is either acrylic or cotton. Acrylic is great as its cheap and comes in a wide variety of colours. The best idea is to find a good brand of yarn and stick to it (although I have to say I'm not particularly good at this), since yarn weights can vary quite significantly between different companies (which is very annoying). The most common brand I use are stylecraft. If you are completely new to crocheting and have never knitted before you will need to build up your yarn stash, gradually increasing the colours you own in specific weights. The weights I use the most are dk and 4ply, which are most common for small amigurumi creations. However I have also started using more crochet cotton (#10 weight), which gives a nice look to smaller items.
3. Toy stuffing. If you are going to be making amigurumi creations you will need to get some toy stuffing. This can be bought from local craft shops or in bulk online. You can also salvage it from old cushions, but this can result in your finished products being rather lumpy, so be warned!
4. A darning needle. You can usually buy multipacks of these from craft shops, including several different sizes. Again the ideal size will depend on what you are making, but with the patterns I make I tend to favour thinner needles over larger ones
5. Scissors. Size and shape doesn't matter too much, but I'd recommend trying to have at least one smaller pair around, as some patterns may require more careful trimming of loose ends

Useful things

1. Embroidery threads. Again this will depend on what you're making, and many crocheters would say they've never had need of them. However, they are often useful when making amigurumi, and I use them for all of the amigurumi people I make. If you aren't into embroidery you don't need to go out and buy a whole load of these, but I would recommend having at least white and black, and then building up your collection as you work through patterns that require them.
2. PVA glue. Again this is rarely used for crochet projects, but I do use it in some of my patterns for creating amigurumi hair, and for strengthening the mobiles I make. Plus I find its a good thing to have around the house for other non-crochet purposes too.
3. A small sewing kit. Some patterns will require a regular sewing needle and certain colours of thread, but again this is a useful thing to keep in your house anyways.
4. An assortment of small beads and buttons. Many of my patterns (mostly the ones involving making clothes for soft toys) require the use of small (around 0.5mm) beads and buttons. These can be bought fairly cheaply online or in some craft stores.