I dont know what SF style is but I thought I could make a suggestion to help get the shape/angle.
I recommend you stick to using a 45 degree angle to make spriting easier. That way, you just "mirror" the two sides of your sprite and it will look correct.
Quick 5 minute example -
A] Start off by outlining your sprite at a normal angle.
B] Add the details and colour.
C] Use graphicsgale to rotate your image to 45 degrees.
D] Clean it up a bit.
E] Clean some more.