To win games when you’re playing with a limited collection, going for an aggressive gameplan is your best bet.
However the path can be pretty narrow to the uninformed. Playing Demon Hunter does make it easier since they have very few “bad cards” compared to the other classes.
The problems you will inevitably face are that it’s fairly easy for anyone to just get a copied deck build, that has a base power level you will find difficult to face with your own decks, especially when you don’t know what all the cards do. These decks can also be quite forgiving, in that a player can make stupid mistakes with a “good deck” but if you can’t punish it, they may get away with it.
So to try to narrow that gap, I advocate for getting key commons and rares opening a few packs here and there from each of the expansions.
To cut down on that frustration, here is a link to a spreadsheet where I list out the staple cards to keep:
As an example, here is a “Starting out” deck for Shaman where a player might have opened a few packs, maybe got a Boggspine Knuckles, and crafted a few cards like another copy of Tour Guide, or Serpentshrine Portal (which are staple commons)
Jonius’ Shaman
Class: Shaman
Format: Wild
1x (1) Beaming Sidekick
1x (1) Blazing Battlemage
2x (1) Lightning Bolt
1x (1) Revolve
1x (1) Safety Inspector
1x (1) Sludge Slurper
1x (1) Southsea Deckhand
1x (1) Surging Tempest
2x (1) Tour Guide
1x (1) Worgen Infiltrator
2x (2) Cagematch Custodian
1x (2) Prize Vendor
1x (2) Rockbiter Weapon
2x (2) Rune Dagger
1x (2) Stormforged Axe
2x (3) Bogstrok Clacker
2x (3) Lava Burst
1x (3) Mana Tide Totem
2x (3) Serpentshrine Portal
1x (3) Whack-A-Gnoll Hammer
2x (5) Bloodlust
1x (5) Boggspine Knuckles
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To use this deck, copy it to your clipboard and create a new deck in Hearthstone
The idea is to build around what you have, and save dust for what you want later, which may be notoriously difficult for some players’ play style.
People will commonly tell you to beeline for a deck or full meta build, which I think just destroys your enjoyment of the game long term. You want to be able to eventually have a collection that doesn’t have “all their eggs in one basket” so to speak. It can be made easier if you pick a few classes and stick to only those classes.