My basic strategy is to maximize my sign-up bonuses while having the best possible effect on my credit score and maintaining healthy relationships with the banks. In practice, this means that every 3-4 months, I apply for 2-4 new cards, carefully selected so that I can easily meet my minimum spending requirements. I always think about my past card history—especially my last churn—and my next churn as well.
If you EVER get rejected for a card, call the bank’s reconsideration line. I have overturned more than a dozen rejections just by calling and reasoning with them. There are several strategies–shifting credit lines from your other card(s) with a particular bank, closing another card in exchange for opening a new one, explaining that you need another one of the same card in order to categorize your spending, etc. The blog Million Mile Secrets has a great article all about how to excel in calling the reconsideration line.
Warning/Disclaimer: During any given churn, I always err on the side of less rather than more, because being greedy can be the death of your credit score, and nobody wants that. There are always more points to be had in a few months, so don’t overdo it.
For my overview on risks and rules of churning, go back to the Credit Card Churning page.