One of the easiest and fastest ways to liven your writing is to avoid the use of the verb to be: am, are, is, was, were, etc. More often than not, you trace a dull passage to the overuse of that annoying little verb. Look at these two examples:
When she finally emerged from the house, Wendy was stunned. The sun was blinding, but the weather was cold. All around her were frozen trees that had broken off at their waists. Everything was both beautiful and awful.
Eliminating the verb to be forces you to think about your method of expression. Usually, this results in a revision of the original thought but in a more poetic and precise manner:
Wendy emerged from the house, stunned by the blinding sun. The trees, broken off at their waists, lay over the yard; each naked branch encased in a thick layer of ice. The day had just begun but held an awful air of beauty about it.
—this isn’t to say that the verb to be is terrible and you should eliminate it completely from your writing. No, you can use the verb, but I’d like to challenge you to use it less than you normally would. It will be tough and difficult, but that’s why it’s a challenge. Good luck.