That's a very broad subject, it highly depends on what type of content you want to do, but I'll try to offer some tips.

-For poses, all you need is Poser and whatever figure you want to make poses for. You'll need an image editor program to work your promos for the store, personally I use Photoshop, but there are many free good ones around these days. One that is widely used is GIMP.

-For textures, be them clothing textures or character skin textures, you'll need an image editor, preferably one that paints on 3d but that's not completely necessary. For painting directly on the 3d files, the one that's used the most is Substance Painter, and you can get that one as a subscription from Adobe OR as a lifetime license from Steam. For free options, you can check Quixel Mixer and Armor Paint, or even Blender - with Blender you'd also be learning a tool to model 3d objects and clothes, and there are cheap plugins to help with specialized things like texturing.

-For modeling, I could go on about many programs, but honestly? I use Blender and it's free. By now I've collected dozens and dozens of paid plugins for it to make things easier and more powerful, but those aren't really necessary. You can find Blender Guru on youtube and check his ever-loved Donut tutorial to figure out how to use the program. And with Blender you can get some plugins that will allow you to do a huge amount of things, like clothes, textures etc.

Ok so to be more specific, here's what I use personally to make my stuff:

-Photoshop for promo editing + some texture things.

-Poses just in Poser itself.

-Characters: I make my morphs in Blender, or the simpler ones straight in Poser. For textures I do some work in Photoshop over skin merchant resources, and/or load stuff in Substance Painter for more detailed or "professional" look (like when I want to make something look more realistic etc)

-Clothes: I use Blender. Addons for it like Garment Tool and Simply Cloth Pro help a lot with this, but most times I model + sculpt the clothes by hand. The Sculpt mode in Blender has tools to help you make believable fabric folds. I UV map them in Blender too, and group them in there as well when it's conforming clothing. And if it's conforming, you gotta learn to rig in Poser.

-Hair: I use Blender and an addon for it called Hair Tool.

-Jewelry etc: I use just straight up Blender.

Now, for all of these, you're gonna have to do a lot of learning. For the parts of the process that are in Poser, there are some tutorials here at Rendo, or Youtube too.

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Feel free to call me Ohki!

Poser Pro 11, Poser 12 and Poser 13, Windows 10, Superfly junkie. My units are milimeters.

Persephone (the computer): AMD Ryzen 9 5900x, RTX 3070 GPU, 96gb ram.