My keyword has 50000 searches monthly but when i find for buying term (cheap, on sale) before my keyword, it has very few searches. Should I use that buying keyword?
It’s best to optimize on keywords that are specific to your product/service, and that individuals in your target audience would be likely to search for. Are people looking for your product/service interested in discounts? If so, then adding cheap or on sale might not be a bad idea. On the other hand, if you’re selling a luxury product, it’s not likely that those words would help you.
You need to do some market research and determine with actual data who your target audience is and the various ways they might be searching for your offering. Once you have that array of information, narrow it down to the specific areas where the competition is lower.
It is about permutation and combination, if the competion is very high on the keyword you are targeting then first go for buying terms and when your site or domain gets authenticity and good page rank then target for that you main keyword