Free Hearthstone Packs
Generally, hearthstone packs are how you obtain cards outside of expansions. There are a few ways you can go about finding free Hearthstone Packs.
1) Promotional Packs (Limit of 10)
These are similar to cd keys, and you would often find them in your physical box copies of blizzard games. Usually, a normal box will have one of these keys and a collector’s edition would have 3. The limit per account however is 10 packs so key them in wisely.
If you don’t have any, you can try asking your friends who play Diablo, Warcraft or Starcraft for their unused keys. Occasionally, promotional events will also give these out, so you might want to check your area if there are any Hearthstone or Blizzard events.
Some sites even sell packs of 10keys, but caveat emptor applies.
2) Event Giveaways
Some events hand out keys that would go to the promotional limit earlier, but others wouldn’t. Some use a bypass by giving you battlenet balance or gift cards.
In Singapore’s Bugis + event then they gave a few $ which could translate into hearthstone packs.
Your own locale might have such tournaments, especially as blizzard prepares for their international invitationals.
3) In Game Quests
Device packs: generally play any game such as tutorial and concede on mobile devices and tablets across OS and get a free pack. (Android and iOS tablet and phone)
Getting 1 class to lvl 10 will net you one pack
There is also the recurring spectate quest that gives out one free pack as a reward.
You can also check the wiki’s list for updates.
If you run out of the free methods and really want to spend some money, you should try the amazon promotions to get the most value out of your dollars.