Directories are best way to get one way links. Especially for new sites.

     There are hundreds of directories but there are also a lot of directories out there where submission is worthless. Avoid your site from submitting spammy directories to stay away from devaluation of your site in search engines. There are certain factors that when combines makes a directory a quality directory. Here are fewer

[1] Age of directory/Domain:-

    It is said that Google give more weight or consider those directories as trusted directories which are older. So if your site is linked from older directories it will help you in ranking better in SERPs.

[2] Page Rank and incoming links:-

    Page rank on Google toolbar and incoming links for other search engines. Especially when unique IP links that point to directory It has better value than if it has No. of back links from one IP. Also quality of those links is important. Page rank should consider for both for home page and from sub page which link to you,

[3] Cost:-

   If it is paid directory than you must consider cost. It is not advisable to pay for $$ for 0 PR Directory. Also consider that for what are you paying? Is it cost for one year or for lifetime listings?

[4] No.of links/Category and No. of categories:-

    It is not recommended to submit site which has no of links (say hundreds)/category.
    It will not help you to get a boost in search engines. If directory having enough and all major category available, it will create relevant results.

[5] No. of page indexed in search engines and SE Rankings:-

    Suppose any directory is banned by Google than it is worthless to submit there. (Why you are submitting to directories?) Search engine rankings and No. of pages indexed by search engines may decide how quality back link it will give to your site.

[6] Traffic:-

   Generally directories are for search engine ranking but if it can provide you a little traffic it is better deal.

[7] Type of links:-

   Before you submit you can check weather directory is SEO friendly or not. What type of URL it has. Directories that can not provide you direct HTML Links may be worthless to submit.

[8] Category of directory:-

   Niche directories are better for getting more relevant links. Example, if your site is related to real estate than you can submit to specific real estate  top directories.

[9] Time for review:-

   Most of paid directories review any listing within 24 hours. You can expect faster review time when you are paying.

[10]Other factors:-

   Like weather directory allow anchor text or not, content of directory (linking from duplicate may adversely affect), No of Scrap listings or quality of outbound links, No. of dead links, editors and quality of editing, type of sites accepted by directory, Submission process, should not be loaded heavily with banners and ads