The knitting needles you use can make or break a knitting experience. Choosing just the right needles for your project and personal preference is important. The following guidelines will help you choose the right needles to buy;
Single point (straight) needles are available in several lengths and used solely for straight knitting. For most projects an 8"-10" needle will be sufficient, but some large projects may require up to 14" single points or the use of a circular needle used back and forth in rows.
Double point needles are used almost only for small circular knitting, such as socks and sleeve cuffs. For most projects a 5"-6" pair will be sufficient. While they are available in lengths up to 10" for larger projects, most large circular projects are worked on circular needles. Whether to use double pints or circulars for small projects like socks, is a matter of personal preference.
Circular needles are used primarily for knitting in the round, but also for large flat projects, such as blankets, that are too big to be worked on single points. Circular needles come in a large variety of lengths, from small 9" needles to 60" needles. For a beginner a 24" circular is a good place to start, but the length you want will depend on the size of the projects you choose to make. Circulars can be both 'fixed' or 'interchangeable'. Interchangeable circulars allow you to attach the same points to different length cords, being more cost effective than buying numerous different lengths of fixed needles.
Bamboo needles are quiet, soft and not very slippery, making them ideal for beginners or delicate lace work.
Wood needles, such as rosewood and birch are usually a little more noisy and a little more slippery than bamboo needles, but less so than metal, making them a good in-between material for any knitter.
Metal needles are slippery and the most noisy type of needle, ideal for speed knitting or any experienced knitter who doesn't mind the noise and harder surface. Metal needles are not recommended for beginner knitters, because the stitches can be difficult to control and fly off the needles, if you're not experienced.