I'd recommend getting a basic ratchet one whilst you're learning, with a nice wide 50mm webbing. Primitive ones are more flexible but take longer to rig, and whilst you're learning you don't need that getting in the way.
I started out with a 15m but a 25m definitely gives more flexibility and room for growth. You could go for a reputable brand name (Gibbon, Elephant, Maverick) if you don't mind spending more (£80ish
) for a more dynamic webbing and better build quality, or you could go for a cheap eBay special (£40ish
) if you intend to leave it up all the time as you'll have to replace it more often as it gets UV damage.
There are some excellent YouTube videos for general technique and tricks. Slacktivity
is a great channel with stuff for beginners through to experts. Always use (tree) protection.