memes

I'd say xenophobes are a reality but fortunately a minority and their xenophobia is generally low intensity. YMMV if you are poorer and/or darker, but I think in general you'll be welcome if you are coming to stay, specially if you make an effort to learn the language. If the place you want to go has a regional language (Galician, Catalan, Basque, Asturian...) nothing gets to most locals' hearts quicker than a foreigner learning that too (and the regional governments normally offer free courses).

If you find that they don't understand you speaking American, just repeat yourself, slower and louder, until they do.

The answer depends on a LOT of things. Most importantly country of origin.

If you're from Latin America, most people won't even notice. Since we already have huge amount of Latin American immigrants, so we are used to it.

If you're from a "white" country, it's very important that you are respectful to the local culture and try to genuinely learn Spanish. This is mostly a problem with tourists instead of immigrants, but most Spaniards hate with passion when foreigners complain about things not being in English/German/french/whatever.

If you're from a "black" country, it depends on where you move to. In some parts of Spain you'll inevitably face a lot of racism. In others, you'll find groups of people that will try to protect you. But as always, there's always at least some racists.

And of course, don't do crime. But that goes for locals too.

And I think this is a global advice. But people will instantly judge if you are lazy or hard-working. If you help your local community without asking much in return, people will probably talk about how hard working you are, and even racists will probably say "for being for country X, he's a nice guy".