[streptomycin]

I use https://www.doctorofcredit.com/ , manual research (there's only so many credit card companies, doesn't take long to check their websites when you're looking for a new card), and also a decent amount of time the credit card companies send me pre-approved offers in the mail and sometimes they are actually pretty good. US Bank recently sent me one for a $750 bonus!

Overall Chase business cards seem to usually have the best deals, and they don't require you to have a "real" business to get them.

It does impact your credit score, so you are correct to be careful if you're going to get a mortgage soon. But in my experience, the effect can't be too big because my credit score is still excellent despite getting a new credit card every couple months.