What an excellent Question!!! I hope your inquiry results in a wave of good advice, ideas, and 'tricks'.
I have found a few things, after trial and error, and more trial and error, that seem to float to the top of the 'success' pile. I'll share for what it's worth... no need to argue folks... this is my experience only.
1) So simple... always smile. Be the friendly Gringo, not the 'demanding' jerk. No matter how frustrated I have been... I always smile, laugh at my own mistakes and bad communications, and show appreciation even when not satisfied. Leave a good impression.
2) Always try to use Spanish... no matter how bad it is. I learned long ago, as a kid growing up in various European cities with foreign service parents, not to expect people in foreign countries to speak English. why would they??? Usually, after you fail... they will try to use their own English, or ask another staff member who does know some English... to assist you. But don't expect it or insist upon it. That's like asking for spit in your food.
3) Do your homework ahead of class! Example: If I am going to Migration or the Bank for something, I will write down all of my questions ahead of time, and then write the Spanish translations. I either memorize the Spanish versions so that I can ask them directly, or I keep the 'list' with me to show the person who is assisting me. But don't stop there... try to imagine, with a little common sense, what the various responses will be... I am always surprised that playing my own Devil's advocate generally is a worthwhile exercise. Sometimes I'm dead-on right. It all helps a little.
4) Don't show your frustration or disagreement. They are doing their jobs, and your opinion isn't going to change crap! Try to show 'trust' in whomever is serving you, and perhaps they will go above and beyond what they do every day. Trust me... it works... even for you. Apologize for your bad Spanish and thank them for everything they are doing. Don't be fake, be honest.
5) Be prepared. Don't show up without receipts, or 'copies of things' they may need. Some 'offices' still use antiquated copy machines... so making a 'copy' could take them 20 minutes. If you already have it for them... show them the original and let them have the copy. They will appreciate less task. Try your best to make their job easier when it comes to assisting you. They'll remember you.
6) Think ahead. If you know you are walking into an 'Escher' drawing... start with asking for any kind of special help that you anticipate, up front... so that you aren't wasting somebody's time. Even asking a security guard if he knows which 'teller' or customer service agent speaks English will put you in the right place. There's nothing more frustrating than 'waiting' in 'ultimately' the wrong line... or having to start over again. That lowers your 'mood' and then you aren't easy to help.
7) Positivity. Don't ask if there is a problem, or what is wrong. Instead, ask if they need, or would like, more information or if they 'want' to review, with you, the information that they already have (which could be wrong because of a simple typo, or your own mistake previously.)
Example: I applied for Permanent Residency after 3 full years of Temporary Rentista Residency. It was easy... I gave them the little info (they still have all of your original Documation from the first time you appled for Temp) that they requested, paid a $200 fee, gave them the reciept; etc. It was 2-3 easy trips to the Migracion office in nearby Quesada. No lines. She told me that it would take 6-9 months. I had a copy of the Expediente. I read it before I left. They had my date of birth off by one day... but I had pointed that out to her earlier. She had a copy of my birth certificate and passport info page (copies I gave her)... so she was aware and was 'supposed' to pass on that info to the main Migration office so that it would be 'corrected' on m new, Permanent cedula. I waited 10 months.. and returned to ask about my status. She said things were moving slow... and to wait 2 more moths. I waited until 13 months had passed... now well into my 4th year of Temp Status. I returned to Migration ... the same woman assisted me, but had little to say. She simply wrote down the name and address of a gov't agency that I should go talk to. I really had no idea what it was that I would talk to them about?? I went anyway. It was the 'Defensoria de los Habitantes' ... who, as the name suggests, assist inhabitants (residents) who have problems with gov't entities or businesses (like banks, or Caja, etc.) I wondered why I should go there... I didn't have any problem with businesses or gov't entities. Just forum commentors!!! LOL!!! They were nice people. The nice lady asked why I was there; I told her that i was instructed to 'go' there by Migration. She told me that there was no problem, but that, they would assist 'me' in making sure that Migration had all the correct information needed for my application for Permanent Residency. I assmed they wanted more info... but she immediately noticed the 'error' in my birthdate. I explained to her that I had informed Migracion of that during my application process; two times... and then gave her my passport and birth certificate for photos; etc. She looked up my caja payment history; etc. We then looked at photos of our cats, discussed the Venezuala issue, talked about Indian Food and the sheer 'size' of the USA compared to tiny CR; among other things. I was the only person there for 6 employees.
In short... I was positive about it all. I didn't act frustrated about this birth date issue; etc. We had a nice time, she made me coffee, and I promised to bring her some Saffron cake. She said I would get a notice from Migration in 15 days as to when I can go to receive my new Resolution letter and get new cedula; etc. My fingers are crossed. But if there are more hurdles; I'll approach it the same exact way. Positive and patient.
Just my two colones.... for what it's worth.
Nobody likes a pushy Gringo.. not even most Americans. So just don't be one. It's not hard.
peace