Choose what should stay centred
Kick, sub-bass and other essential anchors often benefit from a stable centre. A centred vocal or lead can remain clear while supporting textures create a wider field around it.
Width is relative. If every element is extremely wide, the mix may feel less focused rather than more spacious.
Use contrasting layers
Try panning complementary parts, using different tones on left and right, or adding a quiet stereo ambience to a centred source.
Check that stereo effects do not create distracting timing differences. Some widening methods rely on phase relationships that can change significantly when summed to mono.
Check mono and different playback systems
Use a mono check and listen for elements that become thin, quiet or disappear. Compare the mix at low volume as well as at a normal level.
If a sound loses too much energy in mono, reduce the widening or choose a more compatible technique. Preserve the musical information that must translate everywhere.