How to make BMX brakes work better?

There are a few things you can do to improve the performance of BMX brakes:

Adjust the brake pads: Make sure the pads are correctly aligned within the brake caliper and that they are close to the rim but not touching it when the brake is not applied.

Tighten and lubricate the cable: Make sure the cable is properly tensioned. If the cable is too loose, the brake pads will not make good contact with the rim. Be sure to lubricate your brake cable to ensure the pull is smooth and linear.

Check the brake pads: Make sure the brake pads are in good condition. If they are worn out, they will not perform as well and may need to be replaced.

Clean the brake pads and rim: Clean the rim with a rag and some rubbing alcohol to remove any buildup of dirt or oil.

Check the rim: Make sure the rim is clean, true and free of any dents. If the rim is out of true or has dents, the brake pads will contact unevenly and that can cause poor braking performance.

Check the brake system for any loose or damaged parts and replace them if necessary

Some riders prefer to switch to different types of brake pads with different compounds, this can change the grip and power of the braking system, so you might want to experiment with different options (Softer/harder compounds) Typically a softer pad will increase braking performance.