honestly, after about 100 flights (with ties lol) and even dress (bb, tyrwit, nordstrom, JOB) and dress pants, its all about the plastic,
ties - i roll em up and put them in a plastic bag (a good israeli one) they never get creased
shirts - i fold them normally, and in between ever shirt i put a plastic (from cleaners)
pants - i fold them in three and put plastic in between them too
never ever had an issue with creases,
and ive done suits too
oh and the topper is, in my suitcases i liek to put dryer sheets, and this way the clothes smell good too when u arrive at ur destination :-)