I will be playing in a campaign soon. My GM has decided to allow Ultimate Psionics from Dreamscar Press. I have always wanted to play a Blue, but I am not sure how well it would work in the AP. Do you think that it would strain "realism" for NPCs to care that the Goblin must be different because he is blue?
Well apparently goblins of the Thistletop tribe are blue-skinned. (This tribe is nearby to the starting town)
Source: http://paizo.com/products/btpy9hg8?Pathfinder-Thistletop-Goblin
That, combined with the fact that Blues are supposed to be very rare would probably make it a DC 15 knowledge local check for NPC's to identify a Blue instead of assuming it's a regular goblin. Of course if you really want to play one, your DM can say they are common enough in the area, most people can identify one on sight, and they are tolerated in human society to whatever degree your DM says. Perhaps somewhere between half-elves and tieflings. Probably as much as half-orcs.
There will be some anti-goblin sentiment early in the adventure, so a rank in Disguise at level 1 may serve you well. Your DM might be nice and toss in a Hat of Disguise early on. Limited in power to only make small creatures look like halflings, and only work for small creatures. What ever to make sure it's only used to make your character fit in.
Alternatively, your DM can write you in with a reason to be accepted. I DMed book 1 with a goblin PC. He arrived in town with a locally famous goblin hunter, a sight unusual enough to make everyone in town remember him. He had a note written by the goblin hunter and the town mayor expressing his permission to be in town; this was a good enough reason to keep any violence from occurring. After a few adventures, you'll have helped the town enough that your character will be celebrated, so this is all a short term problem.
As always, if you and your DM work together, you can make it work.