Where can I buy ETH?

Excuse me, I'm new to the cryptocurrency world and I'm interested in purchasing some ETH. Could you possibly direct me to where I could make such a purchase? I've heard about exchanges but I'm not quite sure which one to choose or how to proceed. Could you please give me some advice on the most reliable and secure platforms to buy ETH? Additionally, are there any special considerations or steps I should take to ensure a smooth and safe transaction? I would greatly appreciate your help and guidance in this matter.