I'm looking to fly from SIN - IAD once a year. Does anybody have suggestions on which season/airline/route to fly with to maximize mileage? As this is a personal trip, I'll be flying in economy. Will be avoiding summertime season as well. I don't have any status in any FFP and I would like to bank my miles into United MileagePlus. Since miles expiry after 18 months of inactivity, it would be best for a non-frequent flyer like me. NOTE: I would not be eligible for Credit Cards in the US as I'm not from there. Unless someone can tell me how to get a US-issued credit card for someone outside the US.