How to make my website appear on yahoo

83% Out of the 400,000 hits/month my website gets comes from search engines.

Even though most of search engines operate in almost the same way still there are tiny differences between the operation of each of them that might result in letting your website rank differently on each of them.

Of course your website will never be listed on a search engine nor will it appear there before you submit it so I am already assuming in this article that you submitted your website to yahoo.
How to make your website show up on the top of the results
The most important elements in search engine ranking are

1) A page title that matches a popular search key phrase
2) A page name or a URL that matches the same popular key phrase
3) Main page keywords that are related to this key phrase
4) Keywords within your page that Are highly related to the Title
5) using header tags, bold and italics to highlight the same key phrase
6) Using meta tags that contain the same key phrase.

In short your whole article must be targeting one key phrase with all of its elements. For example in this article the key phrase is "How to make my website appear on yahoo"
If you did all of those steps then shortly your website will show on the top of search engine results provided that its frequently updated.
The differences between yahoo and Google

Yahoo focuses more on keyword density which means the number of times "How to make my website appear on yahoo" is mentioned in this article will affect my yahoo ranking more.

Yahoo prefers older websites, that's why you can rank on the top results of Google during the second week of your website's launch but you can hardly do it with yahoo.

These differences are really tiny except for the time difference which could result in letting your pages show on yahoo a bit latter than they did with Google.

Start by optimizing your site for Google and as the time passes you will find it listed on yahoo too since the algorithm is almost the same.