sorry, this answer will be quite long.
anyways, there's a lot of methods. but there's a few things i personally consider when naming cn original characters:
-motif/theme/personality
-rank or class (if applicable)
-importance (if applicable)
-does it sound good/ok?

using motifs or types of characters might be easiest to start with.
if your character is a warrior, you might want to incorporate hanzi that mean strength or fierceness. if they are a doctor, maybe you'll want to use a medicinal herb. maybe your character is associated with the wind, you could use the hanzi for wind in their name. or if they're associated with a season such as winter you could think of using "snow" or "cold" and so on. if they're a person with a gentle personality, perhaps you'll use the hanzi for "warm" or "soft." or maybe you can go the other way for irony, such as using the hanzi "ice" for someone who has a loving heart. maybe you have a quartet of characters and want them all to have a connecting theme. for example, using the flowers of the four seasons, so you could implement each season's flower into the separate names.

for class and/or rank, if applicable, it might be more difficult to decide. for a noble character, it's likely their name wouldn't be something common and simple such as "xiao bai" (unless as a nickname), and rather something literary or refined. poems, literary texts, idioms, etc might be a good place to start if you're feeling somewhat brave.
some families might even have a generation name. usually they're in accordance to a recorded generational poem, so common/lower class people might not use it. in modern times, generation names seem to be used less frequently but they do still exist (in fact, my cn name was decided from a generational poem).
for those that weren't nobility, it's often that names were chosen based off what parents wished for their children, or based on the environment where the child was born. for example, xiao ming as in "brightness" to wish a child will grow up smart. or even, for example, luo binghe, where he was found at the luo river. they can be really simple names!

importance, if applicable, is also noteworthy (to the point i wonder if i should mention it). although there are some ways to interpret this.
1) character importance to the story; maybe you'd want to put more effort into a beautiful or interesting name. not just for main characters but side supporting characters, or even a minor character if they have a specific role. otherwise i think it's fine to just use randomly chosen hanzi for names as long as it sounds ok/nice.
2) importance to a character, or importance to the story plot. maybe it's plot important? maybe a character takes pride in their family/clan name, or maybe a character renames themself after going through a bunch of trials.

lastly, does it sound good? easy to overlook but also quite important. you don't want a bad sounding name. of course, unless it's on purpose. such as a running gag to make fun of a character, or to be a homonym with another phrase/word to imply something, that sort of thing. it might be difficult to decide through sound, but if you know some cn then you already have an advantage over those who don't.

another minor thing is that some specific hanzi or phrases may be (traditionally) only used for men or only for women. i'll leave you to decide what to make of that.

to be honest, wikipedia and baidu are good places to start

-for the ming dynasty specifically, 《Q版大明衣冠图志》is a book that is commonly referenced and used. highly recommend.
-《中国妆束：大唐女儿行》 is not necessarily clothing, but makeup styles during the tang dynasty and is greatly recommended if you are interested in that sort of thing.
-for armor, i frequently use 《画说中国历代甲胄》 as reference. they have armor styles through the dynasties (though the older dynasties are questionable in accuracy) and it is easy to read. how to wear the armor is demonstrated through the pictures as well.
-as an overall dictionary reference, 《中国古代服饰辞典》 is full of information ranging from clothes to accessories of almost all dynasties. however there are little pictures and mostly text, so it is not recommended to use if you cannot read much chinese.

otherwise murals/paintings and statues are often used, and most likely the most accurate reference since they are primary sources. but it requires individual and specific research. visiting museums, or seeing if they display photographs and information of artifacts on websites, is highly recommended.

i also enjoy watching videos that demonstrate how the clothing is worn or made. for example, MingHuaTang-HanFu on youtube has a few videos with english subs. often times you can find videos from amateur historical hanfu enthusiasts on douyin and bilibili too, but it can be difficult to determine if they are accurate or not. some cdramas or games are fine too (sometimes) to reference costume design, but note that theyre not usually accurate since they're guzhuang. some of the best costumes have more accurate resemblance to historical dynastic clothing while taking some liberties to make the costume look more interesting. basically if i see sparkly sequins or leather skirts/pants, i'm going to throw hands.

on a note for qing dynasty, ive heard that there arent many books that is, well, particularly good for reference. from what i've read, the best is to look for blog posts and etc. online from historians or amateur collectors and gather information from there. this also applies to other dynasties, though the older the dynasty the more difficult it becomes (preservation reasons)

im glad you liked gujian3!!

for other games (i assume similar to gj3 and also in cn), it might be a bit limited in english.... there's always the classic sword and fairy series as well as xuan yuan sword (i have little experience with the latter). although, some upcoming games that i've been interested in are "when the wind meets" and "black myth wukong"

the other two gujian games are also very intriguing, but the chinese in them is apparently very literary and difficult to understand hahaha... though, there are cdrama adaptations of gj1 and gj2 that i found decently fun watching if youre interested in the franchise (as long as you can get past the poor cgi and sfx LOL)

some non-3d but also non-wuxia/xianxia esque games that i recommend are "the rewinder" (mystery puzzle, lots of chinese folklore) and "legend of tianding" (side scroller beat em up with taiwanese hokkien, based on real life history)