When your side has about 25+ points, normally you want to bid game. Sometimes the opponents sacrifice.
When the opponents don't have many points, lead trumps.
Why? They will normally rely on ruffing as much as possible, in order to make tricks (since they are lacking high card points). Let's take an example from recent play
In the bidding 2♥ was alerted as not forcing. Partners bid of 2♠ and then 3♠ shows a good hand, probably 14 or 15+ points and a good suit with a distributional hand.
In summary, the opponents have less than half the points in the pack but are declaring on the 5 level - they will be relying on ruffs for tricks, lead a trump and hopefully get in again to lead another trump. Each trump lead is 1 less trick for the opponents on this deal.
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
Losing trick count bidding
Favourable vulnerability
Be a nuisance
Big trump fits
What does 3♥ show?
Mental game
6+ card suits
Use puppet stayman more
Don't push slam in competition
The unusual 2♠ bid
Intermediate jumps
Conventions
Choice of equal cards
Don't false card
Never preempt with 11 points
Is the bid forcing?
Double, Double
Double 1NT, next double
Counting Habit #1
Opener rebidding bad suits
Responder bidding bad suits
2♦ opening
Don't split honors