>>34925668I'm assuming you're asking about novelai. If you pay for the highest tier ($25/mo currently), you get unlimited standard size images (I think it's the smallest portraits at 512x768). It's worth it for me since I go through a lot of experimentation. It also comes with 10k credits a month which can be used for extra features (variations, img2img, larger images, etc). On the lower plans you need to pay credits per any image.
As for tips, you probably need at least a few shared qualities to get the AI to reliably re-create characters past the name. So for Rushia expect to include green hair, double bun, small breasts or flat chest, and red eyes at minimum. After that, it depends on what you're going for. Some type of environment (bedroom, forest, etc.) will help a lot. Clothing + clothing colors are a no-brainer. And then positions and expressions can help put the finishing touches onto the artwork. Don't be afraid to look up tags on the various boorus if you have an idea, but don't know the exact phrase. The text input is pretty good at suggesting auto-completes, but it definitely recognizes some tags that aren't in the list. (Yes that includes some naughty phrases, I'll let you figure those out)
I'm not sure if these are placebos, but I've also found that "depth of field" and "cel shaded" can sometimes help the AI bring together more complicated setups. If a multi word phrase doesn't seem to be working quite right, try replacing the space with an underscore, the AI seems to better parse phrases together that way
