Rush hour traffic is not the best as you can get caught on the N3. Ideally, I would suggest, taking the road up the left side of Intel, turn right at top, follow road until it hits T-junction, turn left and follow signs for Clonee. Get on N3 until M50.
Coming back from airport I normally go past St Margarets to Kilshane Cross and from there to Blanchardstown, then onto N3 to Clonee and to Leixlip. Its a pig of a commute and there is no easy route and expect heavy traffic in the evenings around Blanch