I have seen lots of websites that use Google Snippets to attract the users.
What is the correct way to use them and in which part of website these are applied?
Days are gone when Google used to pick your web page meta description (you may see it in the source of your web page- right click >> view source) to show in the search results as snippet (the text you see below each search result).
But now Google picks content to show as snippet in search result from your web page content what matches best to the user query.
So write content on your website focused to your potential customers.
hope this helps,
But Google still relies on meta tags, i have noted so many times and also gives worth to the content too. But I have seen some sites in organic links showing the location map.
Do u know how it is done?
Yes, Google shows location map with search results but only for localized queries, say you are sitting in Delhi and searching for "web design New Delhi" for this kind of query Google will show location map with search results.
Hope this helps,