We renewed our cards recently, this time hiring a legal assistant here in La Paz Yolanda. I'd highly recommend anyone going through this process do the same, for about $125-150/person, they take care of everything at their local office or even will come to the boat. You sign some papers and wait about two weeks to go to immigration to give your fingerprints, which the legal assistant can drive you to. Much easier this go around. In Puerto Vallarta we would've used Saira. You can message her here on Facebook, Helping Foreigners Living in Mexico
As for those just starting out, I'd even more heavily recommend a legal assistant. You still have to start the process yourself by setting up the appointment in the USA, but then once done there a legal assistant can take over.
For us, aka Ramona, getting the initial appointment was the toughest part last year. This month, we have friends on Volare starting the residency process and after many hours they found that Los Angeles, San Diego, Tucson, Phoenix and Calexico had offices they could use (no prerequisite that you live within their district). The email to try to get an appointment in Los Angeles is firstname.lastname@example.org. Calexico had an actual person answer the phone to set up an appointment, Phoenix had an online system with several appointments available as soon as the next day. I've also been told Tucson has someone answering phones.
For Monica and I, we are now legal temp residents until 2021!