I am not entirely sure what you are asking, but here is the meaning of each: Go about: To 'go about' one's business: To do their business. Go after: To 'go after' someone: To go next, or to chase someone. Go against: To 'go against': Go in opposition to. Get up: 'Get up' off the ground: To raise oneself off the ground. Get the better of me: He 'got the better of me' in that fight!: He won the fight/to win a victory over. As you can see, these all have very different character and function. At the same time, they are all very casual words and would be used in spoken English. They are very common among native speakers. I hope I could help in some way.

I think I understand your question. No, you cannot get the meaning of the phrase out of the individual words or the way they are combined. These are "idiomatic" phrases and you just need to learn the meaning of the entire phrase. They are not logical combinations of the meaning of the individual words in them.