Your CV is what sells you. Even if you submit a covering letter, hiring managers will often look at your CV first to assess whether you have the right knowledge and skills for the job. They will look at your experience and previous positions to see what you know, so make sure your CV is going to sell you.
First of all, look at the formatting. Make sure it is set out in a non-complicated format that is going to be easy to read. Everything should be clear, so be careful about the spacing you use.
Your other main concern is the content. Use a mixture of buzzwords to attract the attention of recruiters, and factual information that sets out what you can actually do. The main purpose of a CV is to bear clear and concise, showing your skills and showing you off to the best of your ability. Concentrate on this and you won’t go far wrong.