The better condition you're in before starting a tour, the more enjoyable it's likely to be, especially early on. So just ride, ride, ride. Hills if you've got 'em. But not so much that you burn out. Listen to your body and mind.

When at home, I never ride with a load. I will up my usual riding time as the tour date approaches. Past the daily average I'm shooting for to compensate for the extra effort required when loaded.

Don't set your goals on tour so high that you are exhausted when you reach your destination. No fun in that(tho occasionally, you may not have a choice.) Think more in terms of hours on the bike than daily mileage. Five or six hours/day pedaling is reasonable, leaving plenty of time and energy for other things.