There’s basically two ways you can go as a beginner:

1) Play it safe. Practise the basic stitches until general holding the yarn and tensioning gets to feel more natural. For this, something like a dishcloth can be a good shout as even with a few beginner mistakes in it, it’s still going to result in something usable. A scarf can work too but as Anna says, they do take a long time so they can get boring. Hats etc complicate things because they’re in the round, but you’ll be used to that from crochet so it’s probably fine.

Since you are already a crocheter though going back to cotton cloths probably sounds insufferable which brings us to…

2) Jump in at the deep end. Find a pattern you really like, and just set about learning what you need to learn to get there. I wanted to make a whole jumper as my first thing, so made a sort of sample rectangle with all the stitches I’d need and then just went for it! Didn’t quite fit in the end, but hey, the horrible acrylic yarn only cost about a tenner in total 😂

Behold my “first project” sampler rectangle, this must have taken me about a fortnight but it did teach me a lot!

Yarn and needles-wise it’s similar to learning crochet. You want a light coloured yarn in something like worsted/aran weight, and generally a 5mm needle is a good place to start to work with it.