Allowable words question

[freosan]

So, I've hit a bit of a snag in my word creation and I'm curious. How did you decide what the restrictions were on phoneme positions in your language? I'm particularly interested if you allow consonant clusters: how did you decide which consonants were or were not permitted to occur together?

I've been trying just saying the words aloud a lot, but in some cases I'm not sure if I'm having trouble because English doesn't have the phonemes I'm using, or because it actually would be physically difficult to pronounce no matter what.

Also, does anyone else have syllabic consonants, and if so, under what circumstances do you let that happen?