It is the sameas a landing page..... makesure it's done right or no one will enter.... Try these steps
1.Target your audience ( Key Topic ):
Optimizing your landing page all starts with your keyword targeting towards your webpage. To build an awesome SEO web page you must know what your targeted key word is and stick to it and not get off track. Grab a piece of paper and write it down in big bold print. Have it next to you while you write your page content and look at it frequently to help keep you on track. This sounds strange, but as you write you may tend to wander off the topic you are focusing on. The best tool I have found is Google Keyword Tool.
2.Know Your Competition :
Do some searches about keyword topic or product to see who has a good ranking and why. Make sure you read their page completely and not just focus on their SEO landing page strategy or techniques, just read the content. Find out how and why their webpage ranked high. Once you have done this, it is time to one up them in the ranking.
3.Writing SEO Content : More 3-11 steps at Hostsb.com
Doorway pages are web pages that are created for spamdexing. This is for spamming the index of a search engine by inserting results for particular phrases with the purpose of sending visitors to a different page. They are also known as bridge pages, portal pages, jump pages, gateway pages, entry pages and by other names. doorway pages that redirect visitors without their knowledge use some form of cloaking. This usually falls under Black Hat SEO.
doorway page is a page that highly optimized for search engine for getting rank but, present another page for user. doorway pages is comes under blackhat seo technique and we should not go for it
