I've found the Keyphrase i wish to rank for but which page do i target ?

I've found the keyphrases i wish to rank for but i'm not sure which page i target. According to the Econsultancy best practice guide the homepage is generally the strongest page and you should use this to target the most important phrases to your business. So if one of my main phrases is "laptop chargers" do i optimise my home page for this phrase or the actual laptop charger page on my site. My homepage is currently optimised for keyphrases related to laptops which is one of the other main products we sell.

Thanks

Paul