Check the address bar, every time
Official domains are usually short and belong to the publisher. Long strings of extra words, unusual endings or hyphenated lookalikes are the most common warning sign.
Never install a launcher from a third-party mirror
Download clients only from the publisher's own site. Mirrors and 'faster download' pages are a common route for bundled software you did not ask for.
Avoid account marketplaces and key resellers
Buying or selling accounts breaches almost every publisher's terms and frequently ends with the account recovered by its original owner.
Use a unique password and check permissions
A password manager entry per game costs nothing. If a site asks to connect to your email or social account, read what it is requesting before agreeing.