I'm trying to optimize adwords for a shopping cart the keywords are related to model numbers e.g. abc mobile company for the model number abc 2215d attracts traffic from keywords like abc 2215d 2215d 2215d sales abc 2215d sales where to buy abc 2215d abc 2215d best price Now here what I did to lower prices is I changed the match type for abc 2215d 2215d to exact and others to phrase. is this the right way. can i get some important tips