I've been working on Solsprak for a novel of mine. Starting with the very basics of phonology definitely helped me figure out what the language would sound like. It's still in the baby stages right now--I need to work more on the tenses and such--but I'd like to finish making the alphabet before I go any further. It has influences from Spanish, Latin, and German. Grammatically, it's similar to German and English. This is my first time colanging, so I'm a pretty huge noob, but it's definitely worth the effort.
Also, I bought a book recently that has helped me figure out syntax and structure. "The Loom of Language" is by Frederick Bodmer and I'd suggest grabbing it at the library if anyone gets the chance. It's not about colanging, but understanding how natural languages are formed and influenced definitely helps make colanging sound more natural, imo.