I'd say take Chersonesos, Campus Scythii, Tanais (really awesome growth rate, you'll have huge city in no time), Byzantium, Nicomedia, Ancyra, and then plan from there. Logically if you follow that strat and the Seleucs and the Armens don't bother you, then Thrace is the next logical target, since you're set to pounce on them from north and south. Then an expansion into Greece. By now you should be strong enough to push the Seleucids into ruin, as at war with Egypt as they are. Armenia is a low priority; they always aim for Hatra. But keep a watchtower near Kotais along the coast, just in case. Strong navy needed.