I forgot to include the following two statements. Thank you very much for your help.

1)He believes a good slogan needs to be short,to have rhythm and above all to sound natural. That’s why slogans tend to go out of date very quickly. 2) He doesn’t want to get away from the pressure of the advertising industry because he thinks that being interested in what he does keeps him young, even though he sometimes feel tired or hurt by people’s criticisms.
3) Brutus believes that his role was in the assassination of Caesar was for the good of Rome
4) He fails to consider the crowd's attitude and feelings and that's why (? other choices?) his words sound ineffectual.
5) Don't change tenses in the middle of a sentences. When describing the various characters or mentioning their own views use the simple present. When referring to historical events you should shift (?) to the past.

2 answers

1)He believes a good slogan needs to be short,to have rhythm and above all to sound natural. That’s why slogans tend to go out of date very quickly.

I would cnahnge this sentence to this

1) He believes a good slogan needs to be short, have rhythm, and above all, sound natural. That's why slogans tend to go out of date very quickly.

2) He doesn’t want to get away from the pressure of the advertising industry because he thinks that being interested in what he does, keeps him young, even though he can sometimes feel tired and get hurt by people’s criticisms.

I added a bit to this sentence.

3) Brutus believes that his role was in the assassination of Caesar was for the good of Rome

You're forgetting the period at the end. The rest looks fine. But, you don't need the was there. I'd change it to this.

Brutus believes that his role in the assassination of Caesar was for the good of rome.

4) He fails to consider the crowd's attitude and feelings and that's why (? other choices?) his words sound ineffectual.

He fails to understand the crowd's attitude and feelings which is why his words are sounding ineffectual.

What you have up there is good as well.

5) Don't change tenses in the middle of a sentences. When describing the various characters or mentioning their own views use the simple present. When referring to historical events you should shift (?) to the past.

Don't change tenses in the middle of a sentence. OR Don't change tenses in the middle of sentences. Whn describing the various characters or mentioning their own viwes, use the simple present. When referring to historical events, you should shift to the past. You could say move back to the past tense. OR use the past tense.
Brutus believes that his role in the assassination of Caesar was for the good of rome.

sorry about this sentence. Do capitialize Rome.