Basically never open 2♣ with a 2 or 3 suiter hand. Shapes like 5440, 5-5, 6-5 etc. For example In the below hand, take a small risk, open 1♣. If it doesn't get passed out, you're in a much better position to bid your hand naturally, for example
You've bid your 6-5 shape already by making 3 bids by the time you hit the 3 level, and you've shown a forcing strong hand. Whereas if you open 2♣, your first natural bid will be on the 3 level! You will never have the room to show this hand.
The most important signals
Double or bid?
Bid as high as possible!
Defending against a multi 2♦
Transfer or not?
Nv compete
How strong vulnerable?
Preempt suit quality
6322 and 7222
2♣ opening
Doubleton lead
Passive lead
When to lead active
1N with 5422
Takeout double
Negative double
Splinters
Competing partscore
Try not double
Ace Ace King
2 level overcall
Lead Trumps #1
Lead Trumps #2
7 card GOOD suit
To open or not, pre-empt or not
Let the opponents play when they are misfitting
The strongest hand
Be practical