Muchas Gracias Gonzalo. Aprendi mucho con su leccion. Pero todavia yo hago muchos errores.

'embarazada',LOL.  Here some common explained errors I've heard from coworkers, bosses and customers, for you guys to get rid of embarrasing (not pregnant! hehe) situations:

(X)  "Te dejé un masaje" (I just left a massage for you)
(OK) "Te dejé un MENsaje" (I just left a message for you)
MASAJE ("mass-ah-eh") means massage.
MENSAJE ("man-sah-eh") means message.

(X) "yo realicé eso" (I carried out that)
(OK) "Yo ME DI CUENTA de eso" (I realized that)

REALIZAR ("real-is-er") means carrying something out, not realizing.
ME DI CUENTA ("meh-dee-quan-tah") means I realized something

(X) "¿cuánto cuesta el caRo?" (How much does the 'expensive' cost?)
(OK) "¿cuánto cuesta el caRRo?" (How much does the car cost?)
CARO (m) ("car-oh") means expensive, costly in terms of money (masculine nouns)
CARA (f) ("car-ah") is just the same for feminine nouns, and it also means 'face'
CARRO ("car-- oh) means car.

(X) "La base es de fieRo" (the base is made of 'fierce')
(OK) "La base es de fieRRo" (the base is made of iron)

FIERO ("fear-oh") means fierce for masculine nouns, while FIERA applies for fem. nouns
FIERRO ("fear--oh") means iron
HIERRO ("year--oh") means also iron

Some other mistakes I've heard often from US friends
(X) "Estás en serio? estás metiendo" (Are you 'seriously'?, you are 'putting in')
(OK) "Hablas en serio? estás mintiendo" (Are you serious?, you are lying)

METIENDO ("me-tean-doh") means putting something in
MINTIENDO ("mean-tean-doh") means lying

(X) "PARA el resto del día" (intended to, assigned to the rest of the day)
(OK) "POR el resto del día) (For the rest of the day)

PARA ("par-ah") means for, but in spanish the above phrase sounds weird
POR ("pore") means by, by means, through, during.

(X) "No tenemos traslador" (we don't have any ...)
(OK) "No tenemos un traductor" (we don't have any translator)

TRADUCTOR ("trade-duke-tore") means translator
TRADUCIR ("trade-do-sir") means translating
'Traslador' means nothing in spanish

(X) "Se caminera el contraCto" (The will be )
(OK) "Se cambiará el contrato" (the contract will be changed)

CAMINERA ("kah-mean-era") seem like someting feminine related to road or highways, Ej. "señal caminera" = road sign
CAMBIARÁ ("came-beer-ah") means future for change.
CONTRATO ("contra-toh") means contract

(X) "Yo usaba tocar tambor en la banda" (I made use of touching drum in the band)
(OK) "Yo solía tocar la batería en la banda" (I used to play the drums in the band)
TAMBOR ("tam-bore") means a single drum. just like those from parades or military tatoos
BATERIA ("battery-ah") means the drums from a music band, electric batteries, or army gun battery
SOLÍA ("soll-lee-ah") means 'used to', while
SOLÍAN ("soll-lean") is for plural
Ella solía bailar (I used to dance), ellos solíaN venir (they used to come)

(X) "No es un trabajo abrido" (it is not a job)
(OK) "No es un trabajo aburrido" (It is not a boring job)
ABURRIDO ("ah-boo-redo ") means boring
abrido means nothing

Cheers,
Gonzalo