I'll give a word of warning here. Most other discworld novels can be read as stand alone books without losing too much.
In fact I started with "Going Postal" and then back tracked to the Watch Series and started with THUD! which is way out of release order.
.I don't think I missed much, and have since read them in order.
Now that I think of it, the Color of Magic is probably one of the worst starting places; I remember I did read that one in the 90's and never touched another
discworld until "Going Postal" and then got really hooked.
However, Raising Steam is very much dependent on having a knowledge of previous discworld books for major plot points, geography, characters and ahhhh'....creatures.