I mostly used Ancestry.com. I used it for free for years but whenever I have a few bucks I’ll pay for a 6-month subscription so I can clean some stuff up. You can use FamilySearch.org for free. That’s run by the Mormons out in Utah. I typically download their documents, upload them to Ancestry and BOOM.

Find a Grave is free to use. I’ve had an aunt’s name but had no idea who she was married to (for example) but then found her husband and my cousins all attached via FaG.

Geni, Wikitree, Wikipedia (depending upon who you’re related to!), etc. are all free places to search. You just have to be careful when you add info. The info is only as good as the people keying it in.