For starters, the HIA website has very good information about exactly what is available on which plans.
Often, better than is available on the insurers' own websites:
http://www.hia.ie/
I have been insured with VHI and Laya and have had no issues with either provider, switched from VHI to Laya for cost reasons.
There are some good recent posts here focused on insurance for children:
http://www.askaboutmoney.com/threads/children-under-6-health-insurance-at-a-minimum.201957/
http://www.askaboutmoney.com/thread...one-plan-500-2-kids-o-one-plan-family.201892/
Keep receipts for any doctor visits, prescriptions etc
You will likely only receive part payment on these from your provider. The remainder can be claimed through the PAYE system under a "MED1" for a 20% tax credit.
You can get separate dental insurance. The cover on medical plans is very limited - and is usually intended to cover checkups \ routine only.
Keep the receipts from emergency dental work, as that can be claimed for tax credits under a "MED2".
If day to day cover is important, pay attention to the excess on the policy.
Optical is part of day to day care, with LAYA Health Secure Plus, I have been able to claim back 50% of the cost for prescription glasses up to €150 per year.
Some plans such as LAYA Simplicity which are very good for hospital cover have a €200 excess for day to day care.
So if you had, for example, 1 GP visit and 1 pair new glasses in the year, you wouldn't actually get any money back as that'd just bring you to the €200 excess.