in your early game you must build trader and roads in every city you have.Than build pesants for garison(one pesant is enaugh in early game for controling the city).Move your armies west to meet briton army,defet them in the open field.Gaul will soon atack you but don,t worry,arky of 5spearwarbands with good general and sreaching women behind the battle line is capable to destroy much greater army of gaul(they always try to charge in your wooden wall).After that I advise taking Samorabiva and any gaulish city you can get.Do not go in to northern italy but you must take Noricum this is key province for later invasions.With your faction heir in the east go and take all province especialy those on north sea.You will see that Gauls have great but very stupid armies and they are easilly defeted.In batles against barbarians just build about 5-6sparmens and good general(I prefer screaching women in every armie couse they couse a rout with their screaching).Later take Britania this will not be so easy,you must know that you have to be patience and that you must be realy good general.Later in my batles with Jullii family I find Axeman are much beter then spearmen,also its great if you have nifht raiders or bersekers,they are best units against romans,and I think they are strongest units in the game becouse they couse fear in the ranks of the orher armies...