How do I convert crypto to bank account?

I've been dabbling in cryptocurrencies for a while now and have built up a small portfolio. But now, I'm at a crossroads. I want to cash out some of my crypto holdings and deposit them into my bank account. The process seems daunting, and I'm not sure where to start. Could you please guide me through the steps? I'm particularly interested in knowing which exchanges or platforms are reliable for this purpose, and what are the associated fees and risks? Also, would it be advisable to convert my crypto to fiat currency all at once, or should I spread it out over a period of time? I'm keen to hear your thoughts on this matter.