When performing any sort of SEO or Search Optimization on a website you need to make plans before you start hacking and slashing at the content. You need to have a damn good idea where you want to be.This Idea will be reflected by your choice of Title.
I would have assumed that you would have done some research, run a few pay per click campaigns to see if there is a market for your product or service and what sort of click through rate you are getting.
The reason I mention pay per click is that it is the quickest way to get clicks on pages bar none, add to this the data you get back from the statistics that will tell you what keyword and phrases produce the most money. Using this information before you properly SEO content can help you save a lot of time in your search engine optimization efforts. As when you make changes it can take some time for these changes to show up in the SERP (Search Engine Results Page)
For on optimization the title tag is the top of my list for the most important element to optimize this is the part the searcher clicks on via the search engines so not only does it have to contain the relevant keywords to make the search engines happy, it may have to contain a hook to get the viewer to click it. Common hooks are, free, cheap, low cost, deals. You do not have to use hooks but if you do have a deal on or offering something for free let you title tell it to sell it.
Keyword and Key phrase Selection With regard to your keyword selection the more specific you are, the less clicks your going to get but the hire proportion of those clicks are going to buy. This is the position we want to be in not only for SEO but for your pay per click as well. if you have a very specific product we want to be there when the buyer is ready to make a purchase not when they are researching what product they want.
Typical search behavior mobile phone example Search 1 mobile phone Search 2 Nokia mobile phone Search 3 Nokia N95 Search 4 Nokia N95 16GB Search 5 Nokia N95 16GB in red
As we see from the example the further along the search we go the more specific we get. When using SEO for your on page optimization we want to target the more specific search 4 and 5 as by this point in the buying process that they are ready to hand over cash as they have done the research and have decided that they want this product. Also the added benefit of being more specific is less competition and the better chance you have of getting to the top of the rankings.