If your starting with Lusotana (sp):
---BUM RUSH carthege!!!!
If you don't they won't attack you BUT, they will build like 2 full stacks. And I don't know about u but I don't like to have powerful armies next to my borders.
---next just chill, disband your super expensive cavarly, and wait till you get some $$.

If you start with Aedui
---BUM RUSH the Arverni!!!
If you don't 260+BC will arrive and you will be fighting both the Romani, and Arverni... not good
---Next make some $$, expand, and keep an eye on the Romans. They will come for you

Same story with the Arverni.

If you start with the Sweboz.
---expand chill... make some $, once ur decently strong for for Gaul, Rome, Dacia, etc...
---beware of the open steppes......

as for the eastern factions.... don't ask me