Be frugal, you can collect miles and points for your flights but i would focus on finding cheap airfare and get out there, I will be goign to europe next week for my 8th time, however this will be the first trip i will stay at a name brand hotel or a hotel that costs more than 100 per night for that matter. rememeber travel is about the places you see i would not wast my youth saving up for first class tickets to get out and see the world,
finally i would recommend against ever planning a "trip of a lifetime" instead focus on a "lifetime of trips" you may find great opertunities just by talking ot friends, i had this girl i was dating(now mrs particlemn) who had to go LAX- amerstdam for 2 days of meeting for work, I found a RT ticket for under 500(it was february) we went for just three nights and then back to the US. it was one of the most fun trips and was only 3 night and over 10,000 miles in the air.