Mixing: The Synth Leads/Strings/Pads

Panning: for synth leads: stereo (fully left/right) or central
               for synth strings: at 4 o'clock

Compression:

Some general settings for leads:

Ratio     : between 2 and 8:1
Attack   : between 3 and 10 ms
Release  : 40 ms / auto
Gain      : between -8 and -10 dB
Knee     : hard

EQ (leads/strings/pads):

muddy frequencies: 250-800 Hz
add body: 100-250 Hz
add clarity: 6-8000 Hz
add brightness: 8-12000 Hz