What's your field?
Are you involved in any research projects that are expected to lead to a publication? Having even one publication in a non-useless journal (i.e. not one of those paper mills that will publish anything for a fee) is going to send a pretty good signal to PhD programs. The best way to show that you can produce publishable research is to already have published research. Although in some fields, a publication coming out of undergrad is already not that uncommon (though not as a first author), and you'd be expected to have more after doing a Masters in the field. You could/should aim to publish your Masters thesis in something other than a thesis repository (i.e. go for a peer-reviewed journal).
Professional experience is pretty much worthless in terms of admissions considerations. A PhD program is very much unlike what you'd do in an industry job, so there isn't much that transfers. Depending on the experience, it can actually send a negative signal. For example, it might raise doubts about whether you intend to stay in academia after getting the PhD.
Again, this is going to vary a little by field. But by and large, PhD programs want you to want to become an academic afterward. They're spending serious cash on you and it doesn't help the department at all if you end up making a ton of money at a company afterward. But if you become a well regarded academic, that boosts the prestige of the program. That's what they exist for.
Moreover, the completion rate among PhD students is about 50%. Your goal in your application will be to convince the admissions committee that you will be one of those who can finish the program. That means proposing a project that is feasible and interesting. If you can frame anything you've done in your MA/MS as a launching point for that project, even better. Note that you're never required to actually work on that project, and nobody ever does what they claim they will do in their application -- if only because interests change. But being able to formulate a clearly defined project isn't trivial, and so it at least signals you can do that.