A. Transfer Partners
You can transfer points at a 1 to 1 ratio from Citi ThankYou. You can also transfer at a 2 to 1.5 airline point from Capital One, and from Marriott at a 3 (Marriott) to 1 airline point transfer ratio. You can also get an additional 5,000 airline points bonus if you transfer in increments of 60,000 Marriott points. (e.g., 60,000 Marriott points become 25,000 airline points, whereas if you only transfer 59,000 Marriott points, you would only get 19,667 airline points).
Other Ratios: Hilton (10 to 1) and Hyatt (2.5 to 1).
B. Flying on Qatar and Partners
You can use Qatar Mileage Calculator to see how many points you will earn on a specific flight or look at the chart below. For partners, you can see the earn rate here. Most economy tickets earn 25% or 50% of miles flown.
C. Other Ways
Promotions: Qatar regularly offers promotions either earning or redeeming points.
Partners: Full list of Rental Car, Hotels, and other partners.