How do I know if a site is safe to buy from?

Could you please enlighten me on how to ascertain the safety of a website when it comes to making purchases? I'm quite concerned about the security of my transactions and personal information. What are the key indicators or checks that I should perform to ensure the legitimacy and trustworthiness of a shopping site? Additionally, are there any specific tools or resources that you would recommend for conducting a thorough safety assessment? Your guidance would be greatly appreciated as I navigate the online shopping world.