I took a look at your site. Theres zero content and a default template. Probably a good idea to apply after you site is complete, not before. I applied to adsense after i had 30 articles and a working template and was approved in days.
what do you mean by Choose Proper Niche! what is niche sites in seo means? please don't mind i don't know the meaning of niche sites.
Choosing proper niche means - choose topics carefully which interests you or in which you are an expert, and write something useful about it.
It was very easy to get Google Adsense account 3-4 months back but now they have tighten their criteria for approval. Once they reject a request for any website then they rarely approve it. Its better to try with some other domain.