My wife and I will travel from Ioannina to Preveza in May. Am having trouble finding easiest way from Preveza to Kefalonia. We are not traveling by car. We plan to stay several days on Kefalonia, then depart for Delphi, then Athens. Help on planning would be greatly appreciated!

Have you looked at rome2rio.com? it can be quite useful -- but be sure to click through to all the underlying threads, as the main pages aren't sensitive to seasonal variations in schedules.

I've checked Rome to Rio; looks like flying is one option.

There are usually boats from both, Nydri and Vassiliki (Lefkas Island) to Fiskardo (Kefalonia).
The summer timetables are not yet published, however.
Timetable of last year: Ferry Tickets to Kefalonia | FERRY TICKETS, LEFKADA ? KEFALONIA ITHAKA, LEFKADA HOLIDAYS, CRUISES, ACCOMMODATION IN LEFKADA, LEFKADA BOAT RENTALS, GENERAL TOURISM SERVICES

There are buses from Preveza to Lefkas and from Lefkas to Nydri - Vassiliki
???? ????? ???????? ?.?. :: Lefkada
???? ????? ???????? ?.?. :: Local
Taxis and taxi boats are available too.

I have done at least part of the route in the reverse direction, by ferry and bus so:
1) Preveza > Lefkada, bus.
2) Lefkada > Nidri, bus.
4) Nidri > Kefalonia(Fiskardo), ferry.
5a) Kefalonia(Sami) > Patras.
5b) Kefalonia(Poros) > Kylini, ferry, then bus to Patras.
That is the interesting route which I took intentionally island hopping.
Another way is to take an intercity bus from Preveza to Patras, then ferry to Kefalonia(Sami).
Then of course reverse the same way back from Kefalonia to Patras.
http://www.ktelprevezas.gr/?module=default&pages_id=1&lang=en
http://www.ktel-lefkadas.gr/?module=default&pages_id=1&lang=en

I understand there are buses from Patras to Delphi in summer, I have never been there.
https://www.ktel-fokidas.gr/en/delphi/delphi-patra-delphi
http://www.ktelachaias.gr/?module=default&pages_id=5&lang=en

....and if you can't find any convenient direct bus, look for journeys with bus change at Nafpaktos.

Thanks neckervd and Retsina for bus and ferry suggestions, very helpful. Seems like a better way to arrive (and leave)!