Orkney, Shetland or elsewhere?

[confusedandemployed]

It's always been a dream of mine to see some of the Scottish isles. This year / next year I may finally get the chance.

Which would you recommend for a first timer, and how best to get there / book accommodation?

TIA

[Fourormore]

Orkney is fabulous, I love it, so much to explore. I've stayed in different cottages each time - I just googled for Orkney cottages.
I drove up. I've done the journey in one go a few times and other times I've stayed in hotels in Falkirk or Inverness. I think the Pentland Ferry is cheaper than the other one that I can't remember the name of.
There are several itineraries available on Google but I'd say definitely see Skara Brae, Tomb of the Eagles and the Italian Chapel. If you can go when there's a folk festival on, so much the better!