If I've sold cigarette cards can I still get a set?
You can collect every single card by looting it from a specific location. There are many maps and guides available on the web which show all the locations.
Alternatively, you can buy Premium Cigarettes from the General Store for $2.50. Every pack will give you a random card. If you sold a card you looted, your only chance is to buy cigarette packs until you get the card again. Any duplicate cards can be sold to a fence for $1.00.
Note that there are 12 sets of 12 cards, for a total of 144 cards.