YES

Using positive words and positive phrases will enhance the tone and improve the effectiveness of your writing. 

Into Practice

Check out how the positive tone improves these sentences:

Negative:      If you do not return your form before 2 August, it will be too late for you to                                   attend the conference. 

Positive:       Please return your form before 2 August to register for this conference.

Negative:      We will not be able to supply you with the books unless your full delivery                                       address is provided. 

Positive:       Please let us have your address so we can deliver the books. 

Negative:      Our shop closes at 10pm every day and all day on Sunday.

Positive:       Our shop opens from 10am to 10pm from Monday to Saturday. 

Negative:     Purchases over $1,000 cannot be approved by anyone else except the Sales                                Manager. 

Positive:       The Sales Manager must approve purchases over $1,000.

Negative:     This model is very popular, but it only does 35 miles per gallon. 

Positive:       This model is very popular, and it does 35 miles per gallon.