I know what you mean about trial and error. I'm really only writing this stuff to get the hang of the grammar, and trying to use sentences that are as complex as ones I'd naturally use in English. I treat the actual vocabulary as 'disposable'; if I remember some of it, great, but if not, that's not so bad. With stuff like participles, I would like to maybe just find more of them used in texts with good translations, although I do have a teacher I can ask about this sort of thing.