I've lived on a ranch for years. Went to rodios etc.
For one, stay away from calves hiding in the grass like the plague. The mother knows where the baby is hiding, don't think you can safely get near and touch it because nothing seems nearby. Some mothers will chase you to the end of the earth for disturbing a calf.
In addition to the other comments about using a jacket to draw their attention, there are other things that are good to know when things go badly (Which is pretty rare)
A word on last resorts. If in the middle of a field with no escapes, remember that a bull is a little like a car; don't run away, move to the side. They're unstoppable but can't turn very well. If you stay beside them as they try to get to you with their head you will go in circles and the bull may give up for a moment and allow you to move away from them. You may have to go through this cycle many times. The very last peice of advice I can give is unreliable and dangerous but every little bit counts. The reason bulls have rings placed in their noses is to control them in small quarters. Their nose is very sensitive and can make them go from agression to fear, but that is cycle that can shift easy in both directions.
The only time I had a bull charge me in a wide open field I was rediculously lucky. (I was also a little stupid, angry, and scared) I was close by and he hadn't built speed so charged a couple steps also and I field-goal kicked him directly in the nose as he was charging and he lost momentum and interest immediately as I sidestepped his slowed charge. He snorted and walked a small distance watching me and I slowly backed and walked away. Very unlikely to hit but at least my show of agression might have made him re-consider. I would only recommend kicking the nose when caught in a full on attack. Turning your back to their head is a guarantee of getting crushed and stomped.
One other note is that cattle kick out to the side, not the rear like horses so there is only a very small safe zone near their shoulder.
And finally a note on agression. Even fawns buy time by charging at wolves. I've seen nature vidoes of a helpless fawn charging a wolf that found it and the wolf running away confused. Very funny to watch and an insight into bluff and bluster. (LAST RESORT ONLY)