As far as the vaginal temps go you just need to be consistent just as oral temping. I have never tried it though.
Are you in your pre-o phase because if so most temps are erratic during that time. They should become less erratic once you have ovulated. My temps are always crazy right before I ovulate. I get a dip and then they go up. GL.
I haven't tried it, but I have heard they're more reliable. Oral temps can be affected by sleeping with your mouth open, for example, so if you're nose is plugged up one day and not the next, you could end up with erratic temps.