Corrosion-resistant screws are the preferred way to fasten pressure treated decking because they will not corrode or loosen over time.
Start the installation by securing each board with a few screws to keep them in place. The majority of fastening will be done once all of the boards are tacked down. The screw length is very important; these screws need to penetrate in the joist by 1-1/2 inches. When it comes to the board ends, predrill to prevent splitting. The screws should be countersunk, but only enough to dimple the surface.
Once all of the decking is in place, snap a chalk line so that the screws can be installed in straight rows over the underlying framing. Each board should recieve 2 screws per joist, spaced about an inch from each edge.