Here are some poems and worksheets to help you understand some important language features you can use in your writing.
Onomatopoia
http://www.superteacherworksheets.com/reading-comp/4th-onomatopoeia.pdf
Metaphor
http://www.superteacherworksheets.com/reading-comp/4th-metaphors.pdf
Similies
http://www.superteacherworksheets.com/reading-comp/4th-similes.pdf