Credit Cards

That just depends on the landlord and what they want to allow - in a competitive market they have tons of applicants with decent credit who are willing to put down multiple times rent, so it doesn't make sense for them to go with a person without credit. One apartment I lived at required a security deposit and last months rent in addition to first month, which makes 3x the rent and they still required and rejected tenants for bad credit (as well as illegally i think requiring an application fee for a bit for replacement roommates before we pointed out that it seemed illegal, if that gives any indication of what typical landlords were asking for and tenants willing to put up with). They did allow cosigning though so one of my roommates had their parents cosign, it just means their parents had to pass the credit check as well as being legally on the hook. That was in the Boston area though so maybe that's a worse area for finding a rental than others, and you'll probably find a few lax landlords here and there who care less, but passing a credit check helps a lot.

It's also nice not having to send 5-10 prospective apartment applications to your parents to co-sign in case any of them get accepted - which I had to do for my first apartment because I had a "thin credit file" for a bit since I was getting started with credit.

And I think 6 months later I had enough credit history to pass the check on my next apartment, so it doesn't take much. I just accept most credit card offers I get in the mail that don't have annual fees, enable auto pay, and stick them all in a box. Every once in a while I buy something at the grocery store on one of them to keep them from being closed due to inactivity (like 4 out of 5 of them don't even care about inactivity so they stay in the box), and now my credit is great. For the most part, I just ignore the credit cards. I only have them to have a credit score.