Identity before the button
Find the product name, developer and official distribution route. A familiar logo and a large download button do not establish who created a package. Prefer the developer’s own link to a store or download page and compare the domain carefully.
Check what you are getting
Read the supported operating systems, processor architecture, license and included content. Distinguish a demo from the full product and a free tier from a trial. A game bundle, a soundtrack and a base game can have similar names while providing different things.
Make the change easy to understand
Back up relevant documents or saves, keep the purchase record and install one new item at a time. Review optional components rather than clicking through automatically. If something fails, record the exact error and the version you installed before seeking help.