Important in or important, writing difficulty, grammar

"It is also important to choose the right words when writing". Use simpler forms of the verb when possible. The infinitive is more direct than the present participle. 'When' is better than 'while' here because 'writing' is an abstract noun which describes a general activity, not one describing a specific, individual action. There are several different ways in which you might convey the same idea: "Choosing the right words is also important when writing." "When writing, it is also important to choose the right words" "The choice of words is also important when writing" All mean very much the same but there is a slightly different emphasis in each one. In the last sentence, notice that 'the choice of words' implies choosing the right words: one would not be expected to make a bad choice! "When" and "while": 'when' is used for a complete time period - in this instance 'writing' is, as I said, the abstract action of writing. 'While' is used to indicate that the activity is continued or continuing and that something else happens at the same time or during that continued activity. "When walking, one foot should be in contact with the ground at all times; when running, both feet may be off the ground at certain times." "While he was walking, he saw the girl running towards him. She was listening to her ipod while [or 'as'] she ran and did not see him."

I would say: It is important to choose right words for grammar

It is also important to choose the right words while writing