You need to use a slicing motion when you use a straight razor, don't like too much but you should use a lateral movement with your normal stroke moving. That and good stretching will provide a closer shave. I don't shave ATG and haven't in about a year. HI_bud_gl aka Sham taught me this stroke and I haven't looked back, since using it I don't need an ATG pass. I just use WTG, XTG, XTG passes. You need to be VERY careful with this stroke, use almost negative pressure, light hands, etc. Don't over do it!

Check out this video made by Sham himself:

SCYTHING MOTION - YouTube