Devoted to ex-pats, exploring resources, challenges, and opportunities

It is always a good idea to register with the Embassy, even if you'll only be in the country a short time.  The State Department in Washington, D.C. receives calls every day asking, "Is my son/daughter/husband, etc. all right?  I haven't heard from them for a while."  These calls, called "welfare and whereabouts" cases, are forwarded to the respective Embassies, where consular officers are assigned to investigate.  Their job is much easier if you have registered with the Embassy.

Call the Embassy and ask for the Consular Section.  Tell them you want to register, and provide the information they ask for, which will be your full name and contact information.  They'll instruct you to inform them of any changes in that information.  Do it.  Your name will be on their calling list in the event of natural disasters or political upheaval.  Tsunamis happen, as do revolutions, terrorist attacks in nightclubs, and more.

If you have gone far from home because you don't want them to find you, you should still register with the Embassy, for safety's sake.

This advice applies to non-American expats in the U.S. and elsewhere.  Your Embassy wants to know how to reach you.  For example, Mexico is trying to reach potential voters in the United States, and they're havving a hard time doing it.

Cultural Considerations (I can't figure out how Part 2 got ahead of Part 1, but that's OK): I've explained this sultural phenomenon before, but it's important to rehearse it here in the context of visas.   In many cultures, it is considered proper to use your influence to help a friend.  By extension, it can be assumed that friends will come to you to ask for favors that might be within your reach but not within theirs.  One such favor is helping to get a visa.  I have a short, unsatisfactory answer you can use: "I'm sorry, I can't help."

In Western cultures, we are raised to believe in the Rule of Law, and that legal and civil decisions should be made on the merits of the case and not because of personal influnce or preference.  We have laws against insider trading and racketeering, and we look unkindly at influence peddling.  It will hurt your foreign friends, in many areas of the world, to hear that you are unable to help them get a visa.  They will take it as "unwilling", not "unable" and will consider you less of a friend. 

Some embassies have "back-channel" procedures by which embassy personnel can endorse/recommend the visa applications of people they know, whether to gain favor or to otherwise move toward government objectives.  No embassy employee will, in good faith, promote the visa application of someone they don't know well and personally.  It's bad for security, which reigns supreme at present.  it also doesn't look good when the person they endorse uses the visa for other than its legal purpose.

Part 2: How visas are issued. 
Visa applicants appear at the window of a consul (or vice consul or consular agent) and present an application.  To get there, they may have had to travel for many hours and stand in line for even more hours.  To prepare their applications, they may have relied on professional services and advisors, all in hopes of making it acceptable.  Once they hand the application and their passport to the consul, a short interview usually follows.  How long do they intend to stay?  Where is the money coming from?  What ties do they have to their homeland?  In short, what evidence is there they will use the visa for its intended and legal purpose of allowing them into the country for a short (non-working) visit, and then return home?

If the consul is satisfied with the answers and the application, the applicant is told to come back later in the day to get the pasport with visa.  Then the person's name and data are checked against a database to see if there is any reason they shouldn't be believed, such as not revealing a previous denial or an over-stay on a previous visa.  if all check out OK, a visa is placed in the passport by stamp or sticker.  If not, there may be a second interview and, if the consul's suspicions are not overcome, the applicant is out of luck, and his/her data will be put into that database of negative information.

As you can see, it can be a costly, tiring, frustrating process, even when all goes well.  I'd love to hear experiences from applicants, successful and not.  (I had one woman pass out when I denied her application)