Google Keyword planner is good tool to find new keywords. Use this tool to find keywords for your website. This tool provide the information about competition of keyword and monthly local searches. This in formation is important for selecting keywords.
The keywords should be relevant and focused to the topic. Use long tail keywords instead of single or two word keywords because suggested keyword is searched more than proper keyword. Use keywords with more number of monthly searches and less competition. This will help you to attain high ranking in SERP.