How to check if a website is safe to buy from?

Could you please provide me with a step-by-step guide on how to determine if a website is SAFE to purchase from? I'm particularly interested in knowing the key factors to consider, such as security certifications, customer reviews, and payment methods. Additionally, what tools or software can I use to enhance my online safety when making purchases online? I'm looking for practical advice that will help me make informed decisions and protect my personal and financial information.