The best opening move for 4-2 in backgammon is 8/4 6/4. Makes the 4-point. Watch it on the board, then read the idea behind it.
The idea behind the move
With 4-2 play 8/4 6/4: two checkers land on the 4-point, the second most valuable point in your home board after the 5-point. You leave no lone checkers.
What comes next
Your next priority is the 5-point: the checkers on the 6- and 8-points reach it with a 1 and a 3, so many rolls will make it.
How to read the move
A move like 24/18 means one checker goes from your 24-point to your 18-point. Points are counted from your side: 24 is the farthest, 1 is the deepest in your home board. “(2)” after a move means you play it with two checkers.