Selected for PLC Combined

Hey all, just been selected for PLC-C this summer (20y/o F). If anyone has any tips I would greatly appreciate it; especially on how to best physically prepare. (Why do most people get dropped, hardest part, tips for the heat, etc) I bought a pair of Tropicals so how best should I break them in/how often should be rucking? Any help or insight at all is welcome. Thanks.