This has been mentioned before but not for a long time. Here's a brief sketch of ideas.
(Optionally, greater Mycenaean exploration and trading posts.)
Minimal rather than non-existent Greek Dark Ages so that there can be some innovations and development. The Mediterranean becomes a Greek lake. A conflict between Persia and the Greeks occurs (probably greatly different than in OTL). Rome and Carthage are butterflied. Greek trading colonies in northern Europe, northwestern Africa, and the coasts of the Red Sea. Direct Greek-Indian trade is set up. Various Greek-influenced states emerge in Europe, North Africa, and the Near East: (Helleno-Celtic, Helleno-Celtiberian, Helleno-Etruscan, Helleno-Illyrian), Helleno-Italic, Helleno-Egyptian, Helleno-Berber, Helleno-Persian, Helleno-Scythian, etc). Greater and sustained contacts between Hellenic and "Indian" cultures leads to a synthesis of the polytheistic faiths of Europe, the Near East, and North Africa as well as the spread of Buddhism among the educated classes of Greek settlements. There'll likely be "Macedonia"-like states that will emerge and unify their peoples and/or conquer their adjacent Greek settlements.