The use of symbols like :: and | and entirely up to your personal preference. And I don’t think using your domain name in your title is a very good idea. You can use your main keywords for the website in your title without repetition. It could be a short descriptive sentence. But be sure to include your main keywords towards the very beginning.
Yes, although it often looks more professional to use the website name/brand rather than the actual domain, eg “Forum - SEO - Sitepoint” rather than “Forum - SEO - sitepoint.com”.
while doing On-page SEO in tiltle of the page use your main keywords and a name of your brand in the end of the title of the page. it actually boost your main keywords, more optimizied in the eyes of google crawler, more easy to index.
1st of all do keyword research.and collect some low competitive and searchable keywords go with buying keywords.after selection your keywords…simply type on Google this keywords.and get inspiration with your competitors.my opinion is about your title its should be “kindle portal reviews” not repeated keywords.
Make your title with your targeted keywords but use it without any reputation. You can use anything , or | to separate keywords in title. Its better to use website name at the end of title only at the home page.
You can use this format for your title, as i suggest you to go with full length of 74 characters of title.
Ex. Kindle Shop, Amazon Kindle Shop in USA | YourSite.com
by this way you are targeting your keyword twice with targeted country or state
I think there is no harm in using your website name in the last. As far has separators are concerned… All of them behave in a similar manner, they do not influence your rankings in any way.