How to create a new language without making it sound like complete gibberish? Read the details!?

I probably won't be of any real, personal help here, but you should post this in Society & Culture > Languages. I'm not saying this is in the wrong section or anything, because by all means you will get some good answers. But it's always good to try and reach a diverse series of people who can help you. And obviously the people who frequent the Languages section (such as myself) have great knowledge of many languages, as well as the history of language in itself so I'm sure you'd find a great deal of good information from there too. Everyone there is about linking you to other stuff, so you'll get some helpful stuff, no doubt.