Adding and subtracting intergers

I do things kind of different and people will say the way I do it is wrong and I don't know how to explain how to get these properly.
 a) 5+ -8 = -3 The way I got the answer to that is pretty much doing 5 - 8 because the negative is well negative like a minus.
b) -4 + 10 = 6 I solved that one by doing 10 - 4, I think the you could put things like that backwards sometimes.
c) 4-9 = -5 This one is kind of hard for me to explain, I flipped it and did 9-4 but knowing the answer would be negative put the negative mark in.
d) -8 - (-9) = 1. This one is pretty much crossing out itself.