flight advice we are flying from Ireland to Portugal

No need to fly both into and out of Dublin crossing the Atlantic. A multi-destination ticket, into one city and home from the other, would save some time and perhaps some money. Many sites and airlines offer these itineraries, which are bought as one ticket.

My thoughts .... Dublin to Porto then return ...Lisbon back to Dublin ?
OR should I do it the opposite way.

It sounds like you already have a round-trip transatlantic ticket to Dublin. If not, I’d also suggest seeing if you could do an open jaws flight into Dublin and home from Lisbon.

With regard to order, I don’t think it matters. Ryanair is the only airline that flies nonstop between Dublin and Porto. For Lisbon, you have the choice of Aer Lingus, TAP, or Ryanair. I’d suggest checking the flight schedule to/from Porto since your options will be more limited there and seeing if it makes more sense to start or end your trip in Porto based on the flight schedule.

Yes, I already have the Dublin ticket ( it was cheaper than flying non stop to Portugal ) I have family in Ireland so its a win win for us.

I want to fly into Lisbon and fly out of Porto after several people have suggested this way. I do believe we will get a car after all and see as much as we can heading North to Porto . 3 days in Lisbon then rent a car and head off...what stops should I NOT miss

Thank you
Pat