Gonna be honest, it's not that hard. The thicker the line, the easier it is to keep straight, I haven't dared try make a 1 pixel straight line, but 10 pixel is relatively easy, it's just a matter of consistency. ᵃⁿᵈ ᵃˡˢᵒ ᵘˢⁱⁿᵍ ᵗʰᵉ ᵘⁿᵈᵒ ᵇᵘᵗᵗᵒⁿ ᵃ ˡᵒᵗ