what's a good toy for a beginner bottom?

Start with something on the smaller side so you can get used to it. Like not something so small that it's not pleasurable but don't be a hero on your very first try. Once you get comfortable you can buy something bigger and keep the original as a warm-up toy. Plug or dildo works, basic toys are usually pretty affordable so you can try one of each. Whatever toy you choose make sure it has flared bottom. Silicone is a good body safe material for anal play but glass or metal are options if you want to try something firmer. Don't use silicon lube if you're getting a silicon toy; use water-based lube. You can get condoms so you have less to clean afterwards but obvs that's more cost. Clean every time with soap and water and sanitize often. Method depends on the material; if it's not battery-powered and it's one of the materials I mentioned earlier you can boil for 10 mins. If you get something fancier it usually comes with instructions for care. Oh and if you see a tear in the silicone flare base or a crack in the glass, that toy is done and you need to throw it away immediately.

Sorry if I'm repeating any info you already know, I just wanted to cover everything I could think of.