9 lucrative credit-card deals new cardholders can get this month ? including up to 75,000 Delta SkyMiles

The fastest way to earn rewards points, cash back, and frequent-flyer miles is to open a new credit card and earn its sign-up or welcome bonus. Keep in mind that we're focusing on the rewards and perks that make these credit cards great options, not things like interest rates and late fees, which can far outweigh the value of any rewards.When you're working to earn credit card rewards, it's important to practice financial discipline, like paying your balances off in full each month, making payments on time, and not spending more than you can afford to pay back. Until April 24, new cardholders can earn 100,000 Marriott Bonvoy points when they spend $5,000 on the card in the first three months. Click here to learn more about the Marriott Bonvoy Brilliant card from Insider Picks' partner, The Points Guy. Sign-up bonus: 100,000 Marriott Bonvoy points (after spending $5,000 in the first three months). The card also offers plenty of perks for Delta flyers, including one free checked bag for each person on the cardholder's reservation; priority boarding so that you can settle in sooner and snag space in the overhead compartments; discounted access to Delta Sky Club lounges; a 20% discount in the form of a statement credit on Delta in-flight purchases; and no foreign-transaction fees. The card offers similar benefits, except for the companion pass, and only has a $95 annual fee that is waived the first year. Click here to learn more about the Gold Delta Amex card from Insider Picks' partner: The Points GuyClick here to learn more about the Platinum Delta Amex card from Insider Picks' partner: The Points Guy Sign-up bonus: Up to 120,000 points (80,000 points after spending $2,000 in the first three months; an additional 40,000 points after spending a total of $5,000 in the first six months). The Premier card offers an annual anniversary free night certificate that can be used at any category 1-7 hotel (hotels that cost 40,000 points per night or less). The American Express Platinum card has one of the highest annual fees of any consumer credit or charge card — $550 — but as AmEx's flagship product, this premium credit card offers a tremendous amount of value to offset that fee. The card earns Membership Rewards points, the currency in AmEx's loyalty program, which can be exchanged for statement credits or cash back, used to book travel through AmEx's travel website, or, to get the most value, transferred to any of 17 airline and three hotel transfer partners (transferable points are among the best). The Platinum Card earns an incredible 5x points on airfare purchased directly from the airline, and offers an airline fee credit of up to $200 each calendar year, and up to $200 in Uber credits each card member year. Click here to learn more about the Wells Fargo Propel card from Insider Picks' partner, The Points Guy. Sign-up bonus: 50,000 points (after spending $4,000 in the first three months). While the card comes with the same sign-up bonus, it earns points on everyday spending faster, nabbing a higher 3x points per dollar spent on travel and dining purchases, and 1x on everything else.