I will only do the beginning.
1 - Albania. Too weak to do much. I prepare for Italian takeover by setting up caches of arms, ammo and medicine in the mountains. When Italians invade I head for the hills and hole up, waging a low intensity guerilla war against Italians, Germans and communists until mid '44.
Maybe at that point I'd intensify and arrange for Allied landings. If no landings I continue until German retreat and take over the country and try to get the Allies to land any troops. I think I should manage not to get invaded by Soviets even without.
2 - Greece.
Plan minimum - not become Soviet satellite - was achieved in OTL. Hence the mission is "best WWII".
Not waste money on Metaxas Line. Buy AT and AA guns plus some artillery tractors. In general invest in PBI and artillery.
Maybe some more money on airplanes? No PZL-24 or Gloster Gladiators but buy Curtis Hawks instead.
Navy - buy more submarines, preferably Italian, on credit to be paid from 1941 onward
Maybe preposition stocks near Albanian border, or start mobilisation by mail in Autumn 1940? Maybe an instant (or simply even stronger than OTL) counteroffensive would be possible, destroying the unprepared Italians and capturing the ports? In any case the submarines should slow down any Italian build up, be it with torpedoes or mines.
With Italians in Albania mangled fall back to Mt. Olympus defensive line before the Germans attack and avoid assassination attempts as this leaves Salonika undefended. Once news of the Germans coming is confirmed, I implement evacuation plans for women and children, dumping them on the British in Cyprus, Palestine and Egypt regardless of their thoughts on the matter. If they not happy I threaten to sign up with the Axis.
Maybe stopping the Germans and Bulgarians at Mt Olympus would be possible? If not - at Thermopyle?
Holding out in Peloponaesus?
Worst case scenario - Crete. Any Falschirmjaeger that come get massacred ...
I think that might stay on the continent, though, as the Germans will soon be busy elsewhere and take most of their airplanes away. And in the mountains and hills it is Isonso Redux. Heh, maybe Rommel gets sent there as he did so well in the mountains in WWI
So, starting '43 I should be able to nibble back territory and by end of '44 be at pre-war border.