MusicRadar Basics: electric guitar part 9 - straps and strap locks
When you first start playing, it's important to keep an eye on your posture. If you're hunched over your guitar all the time, or play standing up but with your guitar hanging by your knees, you might find yourself with a sore back pretty quickly.
When seated, your best bet is to try and keep your back reasonably straight, and balance the guitar on you preferential leg.
Some guitarists cross their legs, and classical guitarists hold their acoustics in a specific way, but the key is to stay reasonably straight and, of course, comfortable.
When standing up, you're going to want to have your guitar at a height where it's easy to play and you're not having to strain, something like this. Of course you can have it as high or as low as you like - this isn't a style lesson - but your back will probably thank us in a few years if you wear it at a middle height, and not right round your ankles.
When buying a strap, it's generally worth buying one that is nice and solid. Certainly don't buy the cheapest one available - why spend hundreds of pounds on a guitar only to see it smash to the ground because of a cheap strap?
It's also worth taking a look at straplocks, which securely fasten the strap to the guitar. There are cheap plastic ones like this, or alternatively metal versions which require some work on the guitar but are pretty much guaranteed never to drop your guitar.