I intend flying to Athens soon .

I havent travelled since the pandemic began  . 

I will get a PCR Covid test done , get a flight ticket and fill out a local PLF form and I can get a visa on arrival  .

Is there anything else that I will need to do 

Have you looked on the Embassy web site.

Just now, norfolkandchance said:

Have you looked on the Embassy web site.

Greek Embassy ?

Or the airline.

Depends on your nationality and also any transit countries too.

You should check with your airline what is required to check-in.

 

As for arrival in Greece, the EU has guidelines which are updated  every 2-4 weeks.... last issue was August 30, so let's hope for a new improved one soon.

https://reopen.europa.eu/en  (and follow the links relevant for you)

 

At the moment, I believe that Thailand is still on List E, which means  that either you are a national of the country of arrival, or you must  satisfy special requirements (like having relatives there, residency rights, well justified work reasons, and similar). Whether this actually applies to Greece is something you should verify.  Also note that your ability to move around, visit indoor venues, restaurants, might be limited as some countries in Europe require a Green Pass (again, check yourself the speficics for Greece).