You have to pick the exchange to sell your Bitcoin based on your country. For most countries, Binance will work fine but if you are from the UK then you can try Coinbase. While you are selling try to avoid p2p where scams like chargebacks are possible so sell directly for fiat and then withdraw to your bank account which maybe slightly expensive but it's the safest. Also don't deposit your BTC before verification, only do that after getting verified since every exchange made KYC mandatory for withdrawals.