Big, big topic, with many facets. To start, let me suggest you google Non-Violent Communication for some specific techniques that can dramatically improve your communication, even if you are the only one using them. You will find descriptions and examples, books and classes. My husband and I both rely on these techniques to help with difficult people, and use them successfully when we have to talk about potentially touchy topics.
But here are a few other observations from your request that I hope you'll find helpful:
Even when we use the much-advised "I feel" messages, if we fall into the common mistake of substituting a concept for a feeling, it won't help and can actually hurt our communication. So these should work well, because they are true feelings: "I feel mad / sad / glad / bored / eager / confused / impatient / content…" and feelings are always legitimate. We all just have them, or they have us. We don't choose them, though we can gradually work with and defuse the negative ones. (Imagine yourself hearing a feeling message from your hunny and notice how you feel in response. Probably not angry, maybe even tender!)
But if, instead of actual feelings, we substitute our thoughts or concepts about the situation, those can complicate matters, because they are open to endless interpretations and argument. So it's not a feeling if you say "I feel unsupported / misunderstood / judged / disrespected / neglected / accused…," and the other person is likely to become defensive and give you his concepts in return, getting neither of you the satisfaction you need and deserve. (Again, imagine yourself hearing an "idea" message from your guy, and notice how you feel in response. Try to understand why that feeling has been aroused.)
So here's just one quick alternative statement you might make, drawn from an example you gave. He's going out for a sandwich and doesn't ask you what you want. Instead of a (passive-agressive) "What about me? (you thoughtless oaf)," say instead what you DO want, perhaps, "Hey, you're going to Subway? I'd LOVE to have a turkey breast with lots of jalapenos. Do you have enough money?"
And if you want sympathy, it can be amazingly helpful to say so honestly, and even give specific instructions if your guy is a bit dense: "Sweetheart, I would SO LOVE IT if you would sit here for five minutes and put your arm around me. I'm feeling miserable right now, and I find that so comforting."