It depends on your country. If you are in the US, I wrote a quick guide to buying crypto from Coinbase on my blog. I think other countries can use Coinbase too, but I'm not sure which ones.
@Dannyboy15 Binance is probably the most unregulated one out there. They do not even mention their country of incorporation or company address on their website or in the general terms & conditions, which is extremely fishy. I believe they are based in China but do not know 100%. I would be cautious.