Check out some of the help and advice pages in this section. There is a lot more to CV writing than meets the eye, and you may be surprised by some of the things you learn.
Be honest with yourself. If you think your CV isn't as strong as it could be, then seek help.
If you want to do it yourself then one potentially good starting point is CV examples (but only top quality CV examples - many poorer quality ones are actually counter-prodictive)
If you want the best results then you are better off with professional help. Just as in other professions, people who work day in day out in a particular profession ( in this case writing CVs) have the know-how, techniques and experience. They know what they are doing,they know what employers look for, and significantly they can almost certainly do a better job at it, and get better results, than most laymen.