I've found that I read cards in groups rather than in singles because context tells the tale much better than a single card. (That's how it works for me, but many others prefer fewer cards and that's okay, too.
)
Anyway, no card always means the same thing, whether you draw more cards or fewer and it's just a matter of sensing what the meaning is in every situation.
Maybe a helpful exercise would be to take the 3 of Swords and put other cards after it, determining what that second card brings to the interpretation. Do this all the way through the deck and, if you keep a journal, write down your interpretations all the way through.
Once you've done the whole deck that way, then shuffle your cards up and put a second card
behind the 3 of Swords, continuing all through the deck as before. For instance, 4 of Coins followed by 3 of Swords, etc. always putting your second card first rather than second.
I don't know if I've explained it in a very understandable way, so if I confused you, let me know and I'll try to do better.
If you want to carry this exercise further, then try adding a 3rd card to the mix. One before 3 of Swords and one after. Or two before and then moving on to two after.
Doing this exercise should help you to see how the meaning of the "negative" card changes when you're reading more than one at a time together.