I have a task to optimize my website keywords but I am quit confused about keyword choosing that I dont understand that which type of keywords should I choose? When I made keywords research I saw that long keywords are in less competition but not so much used by user and I saw the short keywords they have louts of searching volume but too much competitions...In this position please suggest me what should I do??
I always optimize for both. Pick a handful of tough keyphrases and GO FOR IT! Then, simultaneously, cast a very very wide net for secondary keywords and keyword phrases.
There's much value in optimizing words this way because the lesser searched terms are extremely specific and ranking for them brings in highly qualified visitors. But that is an obvious SEO benefit. What most optimisers don't realize is that these obscure, rarely searched terms (that have little competition) enforce your primary keyword targets. They add intelligence to your web page's copy (textual content). The search engine understands the relationship between words, phrases, abbreviations, acronyms, verb tenses, synonyms etc. and will add value to your content as a result of being unique and well-crafted. Composing your sentences. Writing well indicates you feel your page is important enough to take the time to put it together correctly (rather than puking out a bunch of keyword nonsense).
Go for longtails mostly as they have less competition and pick only some less competitive short keywords. Try to get keywords having up to 3-4 tails, you'd find a lot of good longtail keywords with decent traffic.
It is true that, long tail keywords having less competition and short tail keywords having high search volume. I suggest you to use both because you are not able to generate business even if you rank top for keywords having less or no search volume.
In order to rank fast then you must take long tail keywords and targeted them and choose some more short term keywords with good amount of search. Give primary preference to your short term keywords and secondary for long term kw. Long term keyword can rank faster in google SERP and also give a bit of support to rank earlier to short term keyword with good search amount.