Thoroughly clean your wicker furniture using a sponge and soapy water. Smooth any rough patches and edges on your furniture with sandpaper. Be sure the piece you're painting is completely dry before moving on to the next step.
Spread your drop cloth in your chosen area. Put on plastic gloves and apply deglosser to the entire piece of wicker furniture, following the manufacturer's instructions on the bottle. Instructions may vary from brand to brand, but typically require you to saturate a rag with deglosser solution and rub it thoroughly over the furniture. Let the furniture dry overnight.
Spray the furniture with the spray primer. Move your arms back and forth in a slow, sweeping motion to ensure that the furniture is thoroughly covered. Walk around the furniture, spraying from different angles, to get even coverage. Let it dry for about an hour.
Spray the furniture with brown spray paint. Again, move your arms slowly in a sweeping motion and walk around the furniture, spraying from different angles, to thoroughly coat every surface of the furniture with brown paint. Let it dry for about an hour.
Evaluate the furniture. If you're unsatisfied with the color, apply another coat of spray paint, following the directions in step 5. With a dark color like brown, it's common to need two coats, but it's not necessary if you like the color after the first coat is applied.