Not sure about the lowest fees but I’ve used coinbase (based in the UK) and it is secure and easy to set up. Accepts credit cards, bank transfers

i dont know what the best way is, but the easiest is coinbase, and if you need privacy you could use a mixer service. I have used EludeMail (it's a free e-mail provider on the Tor network, also has bitcoin mixer and monero exchange), did not have any problems.

I am a lazy person, so I just purchase via coinbase

I've only used Binance so far, but I understand there's a ton of other exchanges out there.

coinbase pro fees are so low