So you're new to playing Xin? Let's see what I can teach you.
Ember Spirit (I'll just call him Xin) is an a very versitile agility carry hero that is good in all states of the game (early, mid, late) he is usually picked for mid laning, thou offlane Xin is not a bad idea if you are playing him for the first time. He is best picked against glass cannons (for excample, SF) who he can easily destroy with hes excellent nukes.You start by leveling flame guard and searing chains because they are your bread and butter early game tools of destruction, leave Sleight of fist for later since it wont do much in the early game. Once you hit level six, you should almost always go for a gank/solokill to set you up for a good start on your battlefury. When you get your battlefury, you can start pushing/jungle farming for your crystalys and after that, daedalus. Your job in teamfights is to spam sleight of fist + chains combo, and keep your flame guard up. if your team Isn't horrible, and you have ok right click dmg, this should lead to a landslide victory (as ones said by Xins wise brother). When you have enough gold, buy blink dagger and boots of travel for more mobility and map control.
Ok, at this point, you should have 4 late game items: battlefury, daedalus, boots of travel and blink dagger. What next? Well for me there are two options, either the items prefered by my own Ember spirit teacher (two divine rapiers) or an assault cuirass + butterfly. As a wise man once said, evasion can make you immortal (note. CAN). assault cuirass is just nice to have if your team lacks armor.
I want to be honest here, I'm not such a good player. I only have 550 h on dota and 40 ember spirit matches (47% win rate) but I'm not horrible so if trust me when I say, this build Really, REALLY (usually) works.
This was my first guide I made so go easy on me! I am happy to get any comments, positive or negative, thank you for reading!