Go with what’s comfortable! Shaving in the direction that the hair grows is not as close of a shave but less likely to produce ingrown hairs. Against the direction of growth gives a closer shave but can cause irritation. For glide, try using a cleansing oil wash like bioderma Huile or Uriage Xemose. Or a shaving cream (not foam or gel, I’ve never used those without getting painful irritation).
For areas with more contours/folds/what have you, the flatter you can make the skin, the better. Try putting your foot on the edge of the tub (or on a step stool if you only have a shower) to stretch it out, and hold the skin taut with one hand.