You can use this tool while searching for ad group ideas or keywords. Keyword planner acts like a workshop that you can use to expand existing network search network campaigns or build new ones. The tool can allow you to search for AdWords tool ideas or keywords, view the performance of a list of keywords, retrieve historic statistics, and develop a new list of keywords by multiplying many keywords lists together. A free keyword planner, AdWords tool can also assist the user in selecting a list of competitive budgets and bids that you can include in your campaigns. You can utilize keyword planner in laying the foundation of a successful online campaign whether you are a highly experienced pro or new to online. All you need is a Google AdWords account and you will be ready to sign in and get on the move.
1 – I’ve found a niche with low competition and good CPC . but the thing is the while doing competition analysis. I observed that most of the sites that are in the top 10 serps ranking are small ecommerce site selling their own product or sites like niche specific classified ad site with low and thin content. What are your suggestions ? Should I go for such keywords ?
3) Google: This is pretty straight forward but it’s the main reason I like it. I search for my main seed keyword in Google, and use the keywords that Google itself highlights in bold on the search results, plus the “Searches related to” section at the bottom to get keyword variations or LSI. That’s basically what Google is telling you that topic is about. No need for a thousands other tools. I use these to optimize the on page of my target pages as well.
* Please note our tool currently assumes Google having ~ 83% of the market, with Bing + Yahoo! splitting the remaining 17% of the market. Actual market conditions may vary significantly from that due to a variety of factors including: search location, search market demographics, how much marketshare mobile search has relative to desktop in that particular vertical, etc.
In addition, you can dig into the paid side of search and find out what keywords your competitors are bidding on, and then leverage those keywords for your own organic benefit if you're not already doing so. Search Metrics does this as well, but I've found SEMRush to provide a greater range of keywords and they save more historical keyword data than Search Metrics.

"I rarely get excited about SEO and SEM tools...But, when it comes to keyword research it is virtually impossible to produce a quality worksheet without software. When I have to perform the same task for my customers, the process is even more daunting and time consuming...there is now a better way to manage huge keyword lists and this tool is called WordStream."

The limit on manual keywords could be higher.  I personally wish we could input 10,000 keywords at a time, instead of 200.  However, I understand the costs that Long Tail Pro has to maintain each time a new manual keyword is input.  Not a deal breaker, I just wish the limit was higher. (To be fair, I don't think most keyword tools have a bulk manual option at all).