Ohlins race shock- setup

[duckling]

My bike came with an old Ohlins shock, just got a seal put in it and now must set it up. I think one must set the preload first, but then setup what are either called compression and rebound damping knobs, or high speed and slow speed hard/soft settings knobs. The shock technician actually described setup in the latter manner. Which makes more sense in practice? The shock has a reservoir with a knob on it, and another clicker at the base of the body. How does one diagnose the way the bike handles and prescribe an adjustment
Thanks for your thoughts

[reelrazor]

The lower adjuster is the rebound (extension) circuit, The one at the reservoir is the compression circuit.
Is there a screw in the middle of the knob of the compression adjuster? That will be the 'high' speed, I believe.