I have next week off work (woohoo) and was thinking I'd love to get into a bit of trail running. I would run 2-3 times per week, usually up to 5k each time.
go to the irish mountain running (imra) website. Look through the events section. Most, if not all have maps of the routes. Try and follow them, get lost, have fun.
Just get out and explore. Crone woods is a good a starting point as any. The only signposts you'll see there are for the Wicklow way. You'll need to follow a map to figure the way to Maulin. Great running to be had around there. Djouce would be a further run but something to aim for another time.