Step one. Write out the main qualities you possess. Try to be objective and write both positive and negative qualities, like selfishness, stubbornness, etc. Say some words about your interests and hobbies. Don't invent anything (this concerns both your qualities and interests). You honesty and sincerity will help you to void problems in future (keep in mind that one day you are supposed to meet you potential soul mate). Just imagine what will you do if it turns out that you can't ski if you have already told him that you are very fond of mountain skiing? He will just decide that his mail order bride doesn't deserve his trust.
As a rule most of ladies prefer to use very general words in their personal ads, such as: kind, honest, sincere; interests: traveling, music, reading, cooking, children and animals. This is OK, but doesn't it seem boring to you? All these personal ads are too impersonal. Keep in mind that trying to make a good Russian mail order bride you lose you individuality, your zest, the very thing that distinguish you from the rest of ladies and make the man pay special attention to you.
From my own experience I can say that intelligent, smart ladies who claim to be equal partners in marriage are the most popular with foreign men.
Don't try to pretend someone else. You are what you are. Remember, if you wish to find your soul mate (I mean not just someone for getting married) you should remain yourself. So, speaking about personal ads, you should describe yourself and not some imaginary ideal, some image that you are fond of. Even if you are a success and he pays attention to this fairy creature, some day you will have to meet him in person and all this fairy-tale, all this myth will be broken to pieces.