If you don't want to get into the churning game, the Fidelity Rewards card is easily the best card. You get 2% back on everything you buy and it goes straight into your retirement account.
That being said, I think you should give the churning game one more shot if you even remotely enjoy traveling. The process is simple:
1. Apply for 2-3 cards with big bonuses assuming your credit score is high enough (700 or above).
2. Meet the minimum threshold on each card to receive the points.
3. Cancel the card after 10 to 11 months so you avoid paying the annual fee.
4. Rinse and repeat 6-12 months later or as you are comfortable.
I've followed this process for 1-1.5 years and my credit score has slowly risen from 710 to 765 in one year. I've also earned 250k miles this year.
Wow apoclater. That's great. This may persuade me to put some effort into this.
But did you use the points for travel or take the cash back? I'm confused as to how you hold onto the points and let them build up if you cancel the account.
Ok, the answer is it depends on the card, but it's not hard to avoid losing miles.
Most airline or hotel co-branded cards (Citi American Airlines, Chase United MileagePlus) will have your miles in your frequent flyer account the statement after your meet your spend threshold. I do not know of any particular co-branded cards that will take your miles away once you spend them, but that doesn't mean it never happens, especially if you do something odd such as cancel immediately following receiving the miles. That also being said, your miles are subject to normal expirations with the airlines, so keep an eye on them if you decide to cancel. As long as you're earning, using, or doing something with your miles your expiration normally gets pushed out.
Cards that give you points with banks (Chase Sapphire Preferred, AmEx Membership Rewards, etc) DO go away if you cancel the card. An easy way to prevent this is just to transfer the miles over to a transfer partner. For example, Chase Sapphire Preferred allows you to transfer points 1:1 to a ton of different partners such as United, Southwest, Amtrak, various hotel chains, etc. Transfer them before you cancel and your points are yours.
I spent a couple months intermittently reading up on all of this before I dove into the game. If you're really interested, spend an hour a night reading some of archives of Frequent Flyer blogs (Million Mile Secrets, View From the Wing, Frugal Travel Guy, etc) and spend some time on the FlyerTalk forums. Not only will you learn how to earn points, but more importantly you'll know how to spend them efficiently. For example, I may have 300k points right now, but I can spend 15k points through British Airways on a domestic roundtrip versus 25-50k through American or United on a domestic roundtrip to the exact same place. Taking the same airlines for example, if I were flying to London I would absolutely choose United over British Airways or American for sheer amount of award seats and lower redemption point and dollar costs. It all depends on the strengths and situations of each frequent flyer program.
If anyone is actually interested in a longer tutorial or FAQ, I'd be happy to post one sometime if there's enough interest. Flying can be really cheap or just flat out free if you're smart and have good credit, which is very moustachian.