I have the same problem. I generally shave WTG first which like you is sideways but at an angle not completly sideways if that makes any sense. I then re-lather and shave ever-so-gently down which would be XTG. I never go for BBS on my neck either when par feels great and has no irritation. i may have to shave again that evening if I am going out but it sure beats ingrown hairs and razor burn. It is important for me at least to make sure my prep is nothing less than perfect or I get the same issues that you are describing here.
Razor: Merkur HD/Merkur HD Slant/Merkur Futur/Merkur Vision/Gillette Fatboy
Brush: Merkur Silvertip Badger/C&E Super Badger
Soap: TOBS Lavender Soap/C&E Sandalwood
Cream: TOBS Avacodo/TOBS Mr. Taylor/C&E Sienna/C&E Sandalwood/AOS Sandalwood/T&H Grafton/Proraso