Always count the opening suit - Even if it seems irrelevant. It doesn't have to be the first thing you do - you can come up with a plan for the full hand, but just make sure you don't play past trick 1 before at least making an attempt at the opening lead - For example this could be the suit. Lets assume the opponents play 4th highest leads.
The inner dialogue needs to acknowledge and remember the led card, the 3♦. You can see the 2 is missing - it is possible it is from a 5 card suit (if the 2 was led, it would be 4 at most), but could be 3. Also it is from the J since East played the Q, denying the Jack.
Recommendation: Assume the most "normal" layout for the suit. a 4-4 is the most normal break, so I assume the lead is from Jxxx and east started with Qxxx. I know the 3 was led. (That is the final product you need before moving to trick 2. If it takes you a while to begin with, take that time - build the habit.) You know you are playing good bridge when you do this every hand, not only because of how much it will help you, but because it means you are concentrating well.
In contrast, we all know the feeling of moving to trick 2 and forgetting pieces of trick 1, that feeling will mean the rest of your game won't perform well either.
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