Total War

I've just installed Rome Remastered, the original was easily my favourite game when I was younger.

What are your favourite battle tactics when attacking and defending in open battles and sieges for each faction?

For example, when playing as the early Romans vs Gaul and other factions that have huge stacks of warbands, I often find I have a smaller army of mostly hastatii - I often win these battles, but what's the best tactic in this situation? Walk the hastatii up and hurl all the javelins you can then play defensively (guard mode) and wait for the warbands to tire and break / flank them with cavalry if you have any?

And during sieges, what's your move? Flaming arrows on the walls to set fire to the rams and concentrate the enemy into fewer choke points?

How outnumbered do you have to be before you just sit it out in the town square?

Tell me your favourite tactics!