Greystones should throw up a good bit more than just doggies - where, what time of day and what tide did you fish, also give us an idea of what rigs you used, baits, hook sizes etc?
You should expect to catch flounder, dabs and plaice, coalies, codling, whiting, bass, rockling and a few more species, but its all dependant on how you are fishing.
A few things to consider :
1) Hook size - size 1 to 4 best
2) Bait used - mack, sandeel, rag, lug, crab and mussel will do, dont be afraid to try a cocktail of 2 or more baits together
3) Bait size - generally a bait of around 3-6 inches would cover most fish
4) Distance fishing at - 5 yards out to 100 yards should give plenty of different fish
5) Rigs used - 3 hook flapper upto 60 yards, a clipped down rig for for further out
6) Time of day - dusk into darkness generally best
7) Tide - incoming tide generally best
This general rule of thumb can be used for most of the beaches from Louth down to Wexford, the wicklow and wexford beaches are fishing quite well at the moment.
Wicklow pier offers a great chance to catch many different fish, fish right down the side of the pier with small hooks, or cast anywhere from 10 to 100 yards - lots of fish around this area.
Heres a handy site to show you some of the more common rigs used for beach fishing
http://www.gemini-tackle.co.uk/rigs.htmlRigs can be shop bought ready made up, or you can make your own. Most just starting of angling would get a few shop bought rigs, then copy them, making your own allows more flexibilty in rig building as you are able to use the bits and pieces you wish, ie different hooks, different lines, different lengths etc.
Hope this helps to point you in the right direction.