It's a good idea to __ (use) plastic bags or paper bags.

The sentence implies a choice between plastic and paper bags, suggesting a preference for one over the other for environmental or practical reasons. The blank likely requires a verb that indicates a choice or preference. Considering common advice regarding environmental impact, the word 'avoid' or 'reuse' would fit contextually, but the prompt specifies to use the word 'use' in parentheses. Therefore, the most direct completion using the provided verb is to state the action of using one type of bag over the other.