Please post your hints as I still need to get all the shards.
Ok, Infamous blast shards hints.
1. I wish I could give this guy credit. I read it as a comment on a site somewhere. While in game, hit Start, then Options, then Heads-Up Display, then change it from Opaque to Faint. This will dim the map, and most importantly dim the water and electricity. However, the blast shards stay bright blue, making them easy to spot.
2. This I didn't read anywhere, I figured it out on accident, but helped with the final island. Especially since this was done during my hard run through. I will tell you the order I did it. When you get to the 3rd island, you are told to go make a bridge functional. When you attempt to do so, you are introduced to the enemy on this island. I died and turned the game off for the night. Then the next day, I played again, and it started me at the nearest medical bed. I was then told to go back and do the bridge. Only this time, I started looking for shards. Since I was not introduced to the enemy with that task, there were no enemies on the island! So I had free reign to go and get the shards. Since this island has the toughest enemies, that was a nice bonus. The last island took me 30 minutes to get the shards since I had no body to take pot shots at me the whole time.
I would assume that if you get to the island, and not die like I did, and just make sure you skip the first task, I'm pretty sure it would work the same, but just in case you find that there are still enemies all around, I figured I would include exactly what I did. That way, if the enemies are there, you can at least try the order that it worked for me.
Other tips:
On my first playthrough years ago, I made the mistake of getting them when I saw them, then used a map at the end to try to get them all. I stayed stuck at 349 for a loooooong time. Since I had another play through needed for the Plat, I figured I would just do the blast shards all over. Unless you started the game with a map and were diligent to begin with, then I would recommend just biting the bullet and starting over. More than likely, you will save yourself several hours of frustration searching street by street looking for those last few.
So, that is what I would recommend, start over, get a good map, and do not leave Neon, until you have them all for that island, then don't leave Warren till you have all for that island. You will make your life a lot easier.
You will see a few discrepancies online regarding island shard count. This is the actual count: Neon 147, Warren 135, Historic 68.
Good luck!