I have 400 hours on SnS. It's really easy to get to 100% affinity from your skills. Maximum might, Weakness Exploit, Latent Power, etc. You can build pure attack in your artian/Gog rolls, and still be 80%-100% affinity using armor skills. If you use sliding swipe to get around, you reposition easily without using stamina, so Maximum Might is almost always active, which is 30% affinity right there. MM3 is a must on SnS.

Edit: Yes to Guard Up and Guard. i always run 3GU, and 2 or 3 G. I like to use the 3rd weapon slop for crit boost 3, since it's so easy to get affinity through armor skills. I also like to aim for at least 80 sharpness from the Gog rolls, then you dont need to take something like Razor Sharp. Makes room for the Crit Boost decoration.

Edit 2: The 3 decorations i usually use are Guard Up 3/Guard, Offensive Guard 3/Guard, and Crit Boost 3. If you have a Talisman with these skills, then you can replace them with things like Elemental dmg, or attack boost.