There's another question about quick&easy creation of metaphors. But that's not really what you're asking. You've asked a very difficult question, essentially a question that is at the core of "How to write good poetry?"
There is no single good recipe to writing good poetry. I can give you a few tips and guidelines, but it's to each poet to find their own way.
First thing is about striking balance between triviality and obscurity of a metaphor. The metaphor should elicit a vivid imagery firmly bound with its subject, and serve more than just obscuring the meanings - it should bring forth the traits the poem tries to focus on - and still, it should be distant enough from the subject you write about.
I understand the outer layer of your poem: light in the sky, rumbling of storm clouds. I don't understand what it tries to tell me. What is "the candid sky of hope?" If you write just about the sky, this confuses the reader into thinking "candid sky of hope" is a metaphor meaning something quite different; they look for hints as to what it means and find none. All the rest refers just to meteorological phenomena. Then, if it's just about the sky, then this is not really a metaphor, it's a try at description, that, due to weird wording looks like a metaphor. If you wanted to write a metaphor about the sky, you'd use "infinite valut" or "blue canopy", not alliterate the name 'sky'.
If your poem doesn't name its subject, then, like in a riddle, provide multiple hints. Try to make sure metaphors are recognizable to be metaphors - simple phrases. If you're not sure, how - use similes. "[plain name] like [metaphor]", to focus on a specific trait without obscuring the subject.
And for goodness sake, stick to one level of metaphors. If you write about subject X, pick any number of metaphors, each related to subject X. But don't use any meta-metaphors - which relate to metaphors related to subject X.