Set the seat height first, until the handles line up with your lower chest rather than your shoulders -- that one setting is what actually gives you the decline angle here, not the tilt of the seat itself. Press forward until your arms extend without hard-locking your elbows, then return slowly rather than letting the weight stack slam down between reps. With your hands locked into a fixed path, there's no balancing act, so you can focus entirely on pushing your lower chest hard through every rep. Because the machine guides you, this is also a safe place to push a set closer to failure than you would on a free bar without a spotter.