Generally speaking you could add additional description (adjectives, adverbs), For example, instead of saying 'The old man walked down the street' you say 'The little old man walked slowly down the empty dusty street'
Another idea to make your language more interesting is to use metaphors and similes or idioms to express ideas indirectly. So, for example, instead of 'it was raining heavily' you can use the idiom, 'it was raining cats and dogs' or instead of 'she felt the breeze on her face' you could say ' the air brushed her face like a mother's gentle kiss'.