High Elf: add Archery, Music as racial skills
Gray Elf: add 2-3 of (Archery, Survival, Law) as racial skills

Dark Elves get Alertness and Find Weakness, and Mist Elves get Alertness and Necromancy. Their High and Grey cousins definitely appreciate Literacy and Dodge, but their skill set could use a little pop to further differentiate them not only from the crowd, but from each other.

Giving both Archery is a logical choice given their dextrous nature and racial affiliation with bows. Obviously Elven Archers and such will have it anyway, but making it racial gives classes such as Barbarian, Thief (and others like Healer that manage to find a sling/bow) better ranged and survival prospects early-game.

The other additions play into and substantiate the manual's claimed distinction between the two; High Elves are characterized as liking to "hunt, frolic, engage in musical and romantic affairs and generally have a good time", while Gray Elves seem to be more serious/"noble"/arrogant.
The italics show where Music for High Elves come from, and although it clearly wouldn't make High Elves overpowered, it would add some fun prospects should an instrument be found or bought. Music's cheerfulness contrasts the more somber additions of Law and Survival for their Gray cousins. I'm aware that Gray Elves start neutral, but they definitely seem the type to know the law and its ramifications even if they don't choose a lawful path. Even though High Elves start lawful, they don't seem the type to bore down on a law textbook or care intensely about the matter. Survival largely stems from the skill's aid in wilderness ambushes and this passage from the manual: "...generally disliked by most other races that have contact with them (which is next to no one on a regular basis... mostly you will meet Gray Elves in a chance encounter — if you notice them at all!).