What advice does the soothsayer give to Caesar?

to not trust anyone

to trust only Brutus

to beware of March 15th

to leave Rome immediately

to beware of March 15th

Explanation:

The soothsayer meets the Caesar in his procession into Rome and asks him to not to go the senate on the 15 of March as he is sure to die on that day if he goes there. The soothsayer does not mention any names or any people to beware of, just a single date that Caesar should avoid.

Importantly, it is a date that Caesar had to go to the senate to deny his crown and to solidify his position more in the senate after his great victory on the frontiers.