The only ways I have seen for this are
1. Wear heels with all your costumes. If it's a costume with boots (like organization XIII) MOST people wear heeled boots.
2. The other person squats a little. This I have seen a few times.
Other then that I don't really know..
Cosplay DA Regular DA
Akicon 2014 (so far):
-OC (Original Series)
-Yui Hirasawa (K-On!)
-Yui Hirasawa (Attack On K-On!)
-Hanji (Attack On Titan)
-Nepgear (Hyperdimension Neptunia)
-Link (Zelda: OOT)
-Miku (Vocaloid, Galaxy Girls [fan models])
Dream cosplays for now:
-Tsuruya-san (Haruhi Suzumiya)
-Kagami Hiiragi (Lucky Star)