The Spanish /t/ and /d/

Castile is a rough, dry and sweltering land in summer and freezing cold in winter, full of castles. Its language may be a reflection of the character of its dwellers, and yet  some of the sounds are mellow, soft and sweet. Like the /t/ and the /d/: 

Place the tip of the tongue against the upper teeth, softly, so softly that the point of the tongue will almost touch the upper teeth, but not quite, when we speak words like "DEDO", "DADO", "TODO", "DATO". Often, the /d/ is so soft that it disappears: "HABLADO", "LIBERTAD"... Listen to native speakers, and then copy them.