SERBMADHAUS
Don't let him make the same mistakes of raging, attacking and plundering Northumbria and Wessex to obtain wealth and fame after becoming lord, then focusing on conquering territories in Norway to expand his influence and territories, and obtain more men and ships and increase his power then focus on conquering England by first attacking Northumbria.
Ragnar in the series wasted a lot of time having to deal with power struggles and idiotic lords and kings of Norway, because he had no ambition, Ragnar just wanted to be an adventurer and explorer but he ended up becoming king because the others wanted to kill him and he killed them first. That's why it's better to focus on conquering Norway and have many cities and towns under his command so that when you go to attack England you don't have to worry about your city being invaded by other Vikings.