Say I'm targetting the keyword phrase: "playing cards" and "red cards" what should I put in my meta tag for Google mostly (yes, I know most of you will say Google doesn't take them into account but adding meta tags doesn't hurt). So shall I write: content="playing cards red" or content="playing, cards, red" - with commas or content="playing cards, red cards". Doesn't the last option seem a bit spammy to SE as it has the word cards repeated? Especially if other keyword phrases I'd be targetting have the word cards in them as well. What format do you use or recommend?
The whole point of the meta keywords element is to provide "exact" keyword phrase you would want to be searchable for. So you would include them all, don't put more than 25 seperate keywords, thats my personal limit when I insert them. Yes, I'm 99.9% sure Google doesn't factor in the keywords meta element.
I would personally use content="playing cards, red cards" , but put the more desired keyphrase before the other, but I would add more keywords in your META tags, I try to keep a maximum of 20.