Watch the paddle path at contact. That tells you which way the ball is going to kick before it even bounces.
Stop watching the ball and start watching that instead.
Most players lock their eyes on the ball and wait to see what happens after the bounce. By then the spin has already done its job and you are already late.
The better approach is to read the serve before it crosses the net.
How to Read the Spin
Paddle moves right to left at contact.

Expect the ball to kick to your right after the bounce. Start moving that way early.
Paddle moves left to right at contact.

Expect the ball to kick to your left. Get your feet moving before it lands.
What to Do With That Information
Once you recognize the spin direction, start moving your feet before the ball reaches you.
- Read the paddle path at contact
- Anticipate the kick direction before the bounce
- Move early so you are already in position when the ball arrives
- Make contact from a balanced, comfortable position instead of scrambling to adjust
The goal is to stop reacting to spin serves and start anticipating them. The more you watch the paddle instead of the ball, the less effective spin serves become against you.