No worries, no worries~ even if you call Wei WuXian/Ying the "black flute dude w/ the donkey" and Lan Zhan/Lan WangJi as that "string dude with amber eyes", as long as you keep in mind that they're so frickin in love (well, at this point maybe only the string dude at first) you're gonna' be fine :)
At first JiangCheng was just "that angry dude" to me, and then I saw the manhua then he became "that purple angry dude". Huaisang was "fan boy" while his older bro is "the angrier dude". "Evil flower man" was JGY while older bro Lan was "serene flute boi". So you see, you're not the only one who uses a different system in order to recognize who is who. It took me a while before I can finally remember this guy's name and his other name and also, what the cultivation world calls him. You're gonna' remember their names one day soon ;)
I really like this manga but I still can't seem to memorize the names so I just usually call them by their hair color or clothes. But every character has similar clothes and hair, what am I supposed to do then?! I still won't stop reading the manga though.