Back again to another hint for pronunciation...

In English, the s consonant before another consonant is always harsh.
That is, you say spare and small the same way ([-sp-],[-sm-]).

In italian, the s is harsh before 'deaf' consonants (-sca-,-sche-,-schi-,-sco-,-scu-,-sf-,-sp-,-sq-,-ss-,-st-), as in english, and soft before 'sounding' ones (-sb-,-sd-,-sg-,-sl-,-sm-,-sn-,-sr-,-sv-), as the english word rose, but with teeth more ahead.
The group -sc- in -scia-/-sce-/-scie-/-sci-/-scio-/-sciu- words is pronounced as the -sh- in the english word show.
The groups -sh-,-sk-,-sw are pronounced as the foreign words from which they come.

Examples

sbaglio (mistake) [ζb-]
sdegno (outrage) [ζd-]
disgelo (thaw) [-ζdξ-]
Islanda (Iceland) [-ζl-]
asma (asthma) [-ζm-]
snaturato (degenerate,inhuman) [ζn-]
sregolato (immoderate) [ζr-]
risvolto (revers) [-ζv-]

mosca (fly) [-ska]
schema (scheme) [ske-]
maschio (male) [-ski-]
scopa (broom) [sko-]
scuro (dark) [sku-]
sforzo (effort) [sf-]
raspare (to rasp) [-sp-]
squadra (team) [sk-]
rosso (red) [-ss-]
stanco (tired) [st-]

lasciare (to let,to leave) [-∫a-]
scelta (choice) [∫e-]
scienza (science) [∫e-]
scelta (choice) [∫e-]
scintilla (spark) [∫i-]
sciocco (fool) [∫o-]
scelta (choice) [∫e-]
sciupare (to spoil,to waste) [∫u-]

Additional notes

Don't worry if you say a deaf s instead of a 'sounding' one inside a word. Italians will understand the same.
Nonetheless, if you pronounce the -sc- group with the wrong s, sometimes you will say a word you didn't mean. For example, scioccare [∫o-] means to shock, but schioccare [skio-] means to snap; scena [∫e-] means scene, but schiena [skie-] means back (shoulders)...