Sorry Grinch if I came across as testy.
Here's what I suggest as a way of getting started, then. Go find some some exercises by Jim Simmerman. He has one that suggests 20 short poetry projects. If you can find his directly, that would be best.
What he's done is to go through a lot of poems and taken out specific manoevers that he's enjoyed. If you have a look at his list, there's really no reason why you can't put your own list together as well. I'd suggest you start with his, because he's got more experience than you do with this sort of stuff, and the moves that he's chosen are very concrete and quite particular. Run through the exercises without trying to necessarily make the twenty projects ( one or two lines each is all that you need) connect. When you've got them done, look them over and look for the connections that are there between them, even though you haven't attempted top put them there. They're connected because you wrote them and because they're your themes. Now put them together making sure that you allow a little bit of a space for both you and the reader to have a bit of a jump between one and the next into a working poem.
When you write the lines, read them aloud and use your breath to measure out the length of each line. Start out with one breath equals one line. Later on you may want to experiment with other measures, but this is a good one to start with.
Simmerman makes a point of saying that you should use each of the senses in your lines as a way of describing or talking about something. It's a good idea even in metrical verse. Imagery is not only visual, and everybody is not primarily a visual person. Make sure you get in as many verbs with concrete references to the senses as you can.
This way, you can pay attention to the form of what your writing in the same way that you can pay attention to the form of a sonnet, but the form you choose is more open and variable. Free verse doesn't mean formless verse.
Anyway, you wanted something more specific. I'm skipping ahead a bit for you. What are some of the things that Heaney (not really free verse now, is he?) or the other guys do that you admire? I'd been hoping to have you build up a list of your own stuff from scratch rather than offering you Simmerman's excellent list. Your own list would be more empowering, since you'd get more of a sense of where lists and choices like this come from, and how they're rooted in your reading and in the poetic conversation. Maybe after you've seen Simmerman's list, you could add a few of your own faves from your own reading. I like starting out, for example, with syllabics and then revising away from them at times. Dick Hugo liked to try to rhyme within perhaps five or six syllables of a word. If you look at Keats, you can see that he spent a lot of time playing with vowels to keep things moving and to keep his associations primed, though of course, he wasn't free verse. Denis Johnson once tossed in a fairly modern invocation to the Gods in an everyday free verse poem. I don't believe it's been published, but the line was ó "Dear Boss of The Angels, Dear Mr. President..." I don't know if you like that one or not, but I'm still envious after almost 40 years. Still tickled as well, tickled as the first time I heard it.
I don't know if this is at all useful for you, or for anybody else, but I'm hoping it might offer something of use. I'd love to see what you or anybody else comes up with, by the way.
All my best, Bob Kaven