I mainly sell electronic products, mobile phones and mp4 looking for some information about the product keyword, who can help me
then check it here : adwords.google.com/select/KeywordToolExternal its the best free tool for keyword research.
I also recommending using the tool mentioned by asadiyah above, type in some product names that you sell and find some keywords. As an advertiser, ideally you are looking for keywords with low advertiser competition and high monthly searches.
The Google Adwords tool is a great place to start, but not very accurate. There are plenty of useful tools for keyword research on the internet for FREE, you just have to find them.
Using that google adwords external keyword tool is really helpful. But you should choose what keyword is right for your language preferences, whether you sell your products in domestic or international.