An effective writer uses a thesaurus to consider the nuances of specific synonyms.
Explanation:
Thesaurus refers to the different words which are similar in meaning or are synonyms. Thesaurus helps in providing alternative word to avoid the repetition of same word in the text. Different words with same meaning are used in different degree. For instance thesaurus for hope can be ambition, achievement, optimisom. Howver, these synonyms are used under different nuances.
The last sentence is an example of a comma splice since 2 independent clauses are connected by only a comma(it needs a coordinating conjunction after the comma or change it to semicolon or period)