Hello,
I have been having mostly DR for ~20 years, and during that time I practiced mindfulness meditation for about 6 years regularly. It did help me to be more present at times, but it was only like flashes or short experiences as you describe. I went on a month long retreat with 8h meditation per day, and other shorter retreats, and it did have an effect during the retreat and for some days after. It had some effect on my sensation of being "present" but not exactly on my derealization. It's like it had some effects on some ingredients of my DR but not on the whole thing. It had some positive aspects, but at times it also fueled my sometimes not so healthy but also not dramatic look for a cure.
I guess tricks depend on what "problem" you are encountering during meditation. I had a lot of trouble, especially in the first years, with unconsciously trying to control my experience during meditation, anything that helped me letting go was a good thing for me. Meditating a lot more helped me to do that on the long run, and one thing that I remember helped me more than many others was something that I used again and again to remind myself that nothing in my meditation experience needs to be judged or controlled (thoughts, difficult emotions, spacing out, control, wanting to stop control or to control control, wanting to stop controlling control, and so on...). That "something" was to remind myself that everything I experience during meditation (even uncontrollable control) can be compared to a tree. Trees all look different, there are big ones, small ones, some with a lot of leaves, some not, and so on. But when you walk in the woods you never think "that tree doesn't look good here, I wouldn't have put it here personally", you just walk there and discover these woods as they are without thinking that they "could be better". That's my two cents trick.
And a piece of advice about meditation, if I may, I went to an organisation that taught meditation for all those years. I got some very valuable things out of it, but it also turned out to be a cult. It started like a very secular organization, people were very normal and very nice. Only when I left did I realize the manipulation had started early on very very gradually. Higher up, some people got beaten (or even bitten...) by the guru, stripped naked and so on, and thought it was a normal thing on the path of enlightenment. So my tip is to be suspicious of any organisation that seems too attractive, of the things that seem too good to be true (as a matter of fact, when I arrived it looked like the opposite of what I would expect from a cult, and I had very good vibes there). By the way, I had a lot of "too good to be true" ideas about meditation as well. Today I realize it did not help me as much as I thought it did, or as much as I was led to think it did.
