No, "to articulate yourself" simply does not sound right to my (native U.S.) ear, at least not with "articulate" in the meaning of "speak clearly." That's just my opinion, I'm not an expert. One could concoct a far-fetched use of a different meaning of the word. "OK, C-3PO. I've unpacked you, assembled one of your arms according to the directions, and turned your power on. Please finish the job. Use that arm to assemble your other arms, legs. Your joints should just snap easily without tools. Go ahead and articulate yourself well."

What say I? It sounds like "business speak." There's a certain type of writing and speaking that's used in some professional environment and used a lot in professional self-help books, articles, and blogs. The style tends to massively overuses reflexive pronouns and misuses words like "articulate."

Wow, this is a difficult one. It seems to be missing the infinitive in its current form ('to articulate') but I would avoid that construction, because with the 'better' hanging around you might end up with a split infinitive :-0 I don't know what 'they' refers to, but I would say: 'They help you to be more articulate.' I found this: http://conjugator.reverso.net/conjugation-english-verb-articulate%20oneself.html. But I would avoid, because as a reflexive verb it sounds bad, even if it is correct.

Incluyo los significados que el Diccionario de la Real Academia de la Lengua Española (RAE) tiene para el verbo 'articular'. Todos indican que es un verbo transitivo. 1. tr. Unir dos o más piezas de modo que mantengan entre sí alguna libertad de movimiento. U. t. c. prnl. 2. tr. Construir algo combinando adecuadamente sus elementos. Articuló un buen discurso. U. t. c. prnl. 3. tr. Pronunciar las palabras clara y distintamente. 4. tr. Producir los sonidos del habla. 5. tr. Der. Proponer medios de prueba o preguntas para los litigantes o los testigos Por su parte Los verbos reflexivos son verbos transitivos cuya acción recae sobre el mismo sujeto que la realiza. Llevan un pronombre p,e levantarse. Me levanto todas las mañanas para ir al colegio,

I don't think the usage of "articulate oneself" is standard, and it doesn't feel right to me. Oxford's definitions and example sentences don't include this usage. https://en.oxforddictionaries.com/definition/articulate I searched the sentence database fraze.it (articulate * self) and none of the sentences included this usage. http://fraze.it/n_search.jsp?hardm=1&t=0&l=0&p=1&q=articulate+*self I would say that the writer confused the meanings of the words "express" and "articulate". Best wishes with your teaching.