Create the illusion of being able to get massive amounts of money at any time while also having the illusion that you're super responsible and trust worthy of said money. The more people willing to loan you more money, with you not using that money all up, is best. And it's a pain in the D.
I was getting punished because I had awful credit. Not because I ruined my credit, but because I didn't have any. I opened the only place that would give me a CC at the time--walmart of all places. I'd buy my gas there monthly, pay it off and just turned my gas money into a monthly bill, and after a couple months I was able to get another credit card (I went with Amex Sky Blue, pretty satisfied with it so far--use it for vacation payments, then pay it off at the end of the month in full, and it gives me points for $100 off flights sometimes.. Pretty simple exchange. It's like an extra step to me of getting my money out of my bank account.) that was actually practical. If I were to do it again, I'd get a bigger better CC with no annual fees, no same-month-fee or total-pay-off fees (you gotta ask about those things, sometimes they're really shady and make you pay in installments, or charge you interest same month. Most I don't think are allowed/don't do that, but still something to watch for), that offered simple cash back on groceries and gas.. Then I could make both of those a simple monthly bill and get some little insignificant pieces back via points. I buy those more frequently than I buy flights.
Things that hurt credit - Anything that makes you look like you need money. For example... Inquiring about your credit (i.e. to get a card, to apply for a loan to a house, etc.) 1 a year of hard inquiries won't hurt.. but 2+ starts to hurt. I didn't care at the time, building credit is a slow burn, so I took the slight hit in exchange for having accounts open and active. Opening a credit card. (Hah!) Only initially though, for similar reasons. Asking for a loan on a house. Not paying bills on time. etc. A credit card company automatically closing your account for non-use and not even informing you about it. (Ask me how I know.)
Things that help your credit - Pretty much who's willing to lend you what and how much and how often. If you're loyal to most credit cards, they'll ask you after a year or so to boost up your credit line. The more people willing to lend you credit, the better off you look. But, really, you don't need tons and tons of credit cards for all of that. Just some slow burning time on the same ones. Subscribe your netflix account, for example, to be paid with it or something, then have auto-pay set up for the credit card, and boom--easy, you can hide the thing and it's just like it's being taken from your bank account. Paid in full each month without fail, constantly getting used.
So, things that are hurting my credit for example:
- I had a credit card closed on me when I never knew it would be closed. I planned on using it each year once a year, and that didn't work out well at all. That was before the walmart CC. Nothing much to be done there.
- Bank of America had my car loan, and I paid them off on time but we had a dispute about the final payment amount--they said I didn't pay it, my bank account showed it was taken out. Lots of arguing over a year in Africa later, they finally say, "Oh, yeah, you did." and closed my account. Well, now I have a closed loan amount on my score, AND I have a 'derogatory remark' because they already labeled it as unpaid by the time we got it sorted through. They fixed it in THEIR books, but they don't give a hell about fixing it on my credit. So, I've got to whip out my writing skills one day and write a nice letter to have it disputed and taken off my record.
- I was trying to get a house loan at one point, and so I was inquiring to my old bank about it. They ran 2 different hard inquiries on my account, and I TOLD them how I made my money, and then they said, "Oh, yeah, sorry, turns out we can't accept your style of income as stable income." So now I have those inquiries on my account for a while too.
If you do ONE little thing wrong, credit drops like 50 bazillion points. If you do something right, it goes up 2.