To save time and efficiently generate negative keywords, try using Wordstream’s services or Google Adwords’ broad match/phrase match options for a large spectrum of keywords.
Again, Google Adwords search query report does offer set keywords for your ad group that you can choose selectively as “negative,” but the list is ideal for a few keywords at best.
Paired with Google Analytics or other PPC metrics systems, you can determine what keywords have performed well, segmented by dates, times and more to maximize the effect of your negative keywords – without breaking the bank.
And if all else fails, look at what the competition is doing in terms of keywords/negative keywords! Depending on the context of your ad or page, you can always refer to pre-set negative keyword lists to give you a better idea.
In a nutshell – be wise about your negative keyword choices, but don’t miss out on an opportunity to engage the viewers that matter, and maximize the effectiveness of your PPC advertisement efforts!