I would depose Tiberius, meaning assassination. Marched around the empire with my legions to strengthen my cause to be emperor with show of force. Then I would go on a major campaign against Parthia and come back with spoils and riches. And for those who disagree, Parthia can be beaten(I mean we did take over Mesopotamia for a while). All you have to do is ally yourself with Armenia, unlike Crassus, and used their land as a base point. Also use their fiercesome calvary.After that campaign, I would do the death choke on the Germans and bring back more slaves and men for the recruitment of the Legion.