The problem the original question addressed is Tex Mex. Many years ago I was an instructor at the US Air Force helicopter school in Wichita Falls, TX. I learned "español" in Key West, FL my hometown. One session we had two students from Mexico and one from Ecuador. I was tutoring all three in instrument flying in Spanish. I got to know them fairly well, and one day I asked one why I could understand him. but couldn't understand the local language. His reply -- "Mi capitan, yo tampoco." Me either!
Go for Spain.

Agree with a lot of the posts above. The important thing is to have a good basis in structure and general vocab. of the language and, later, supplement that with the slang/colloquialisms/specific vocabulary of the region or linguistic community with whom you will interacting. Where your patients are from and education level will have a lot to do with what kind of Spanish they speak. There are actually books and classes on Spanglish and even pachuco/calo if you are interested.

Do drop the "lisp," though, as it has a tendency to sound pretentious to Latin American ears when used by a non-Spaniard.

I would recommend keeping the lisp! I like that it is such a distinctive marker of where I learned Spanish. However, it might make sense to soften it a bit in conversations with Latin Americans (for example, when saying "theta" for "zeta," move your tongue back behind your front teeth rather than placing it between them). I really enjoy using my castilian pronunciation--and would find it nearly impossible to switch back and forth from "lisp" to "no lisp" cleanly (I think I would lisp half the time, and not the other half, and that would sound strange!!).

As has been pointed out here and elsewhere, it's not likely you will be able to completely drop your American accent--so to add another layer of accent-masking to the whole mess seems to me to make everything even more confusing!! My advice, however, would be to be sure you know the handful of words that mean dramatically different things in different places, and work around those!

My son is currently studying Castellano in Madrid and when he came home for the Holidays, I got such a kick out of his accent. The Spanish spoken in our family is the typical California/Mexican/ Spanglish. My father refers to tortillas as discos for cryin' out loud! - what a joker. My dad was born in Mexico, by the way. Anyway, my son said it took some getting used to (the accent and the use of different words and expressions) but after being in Madrid for three months and then coming home, he found our accents strange. Speaking to the grandparents was a hoot!

I'll be in Madrid in a couple of weeks (my very first time in Spain - I can't wait!) and I sure hope I'll be able to communicate with the natives...my son included.
Saludos,
Mama Chula

I don't agree with the suggestion of changing your accent because it sounds "snob".

The people here and there speaks in different ways, which must be respected as a cultural richness, and in not way should prevent someone of using his/her own accent.

Anyway, there are lots of accents in spanish, but it is usually not difficult to understand someone with a different accent.

If I were american and wanted to study spanish, I would try to do it with the mexican-american accent, which is the one you will probably most use.

However, there is a unified gramatic, phonetic and synthactic standard (agreed by the language academies of all spanish-speaking countries).

I will say that studying spanish in Madrid and the surroundings is a good idea, since the accent vary very slightly of what the common standard states.

Fernando

Fernando:

One point: I never said that the Iberian accent was inherently snobbish, only that it sounds a bit pretentious when attempted by a non-Spaniard. It's kinda like an American affecting a British accent in English to sound more sophisticated.

At any rate, the structure of the language is more or less the same everywhere. Vocabulary and accent issues are fairly minor in most cases, and easily learned.

Cooter - It depends on where and how you learned your Spanish. Have you ever met a foreigner in the USA who's native tongue was not English but had learned it in an academy somewhere in Europe that taught him with an English accent? Did you expect him to change it immediately once he arrived in the USA? He probably would if he was interacting with Americans for any length of time but not right away.