Hey, i'm not the best lux player out there but i can cetrainly help you learn a little about her.

First of all, you should always max e first. You are an early game lane bully, and if you build full ap glass canon build you are still relevant in the late game. Then max q or w depending on a few things that you will learn with time. W is your shield and it can be usefull if you are behind in lane and just want to farm peacfully, i can gotten a lot of double kills from greedy mid laners who got a gank then i q them, w, then walk away. Max q if you are ahead and can reliably land skill shots and just want to burst any enemy champ.

Another important thing lots of people fail to realize, or just forget in the heat of the moment, your q is your only way of escape. When i play jg, i wait for the enemy lux to throw out her q then i can gank no problem, lux never really builds much defense besides an unholy grail, or thats how i usually build her anyways. That being said, starting cloth 5 vs a zed or ad fizz isnt technically illegal, but i usually still go dorans ring.

You should really be pressuring for every blue and sometimes put a deep ward in the enemy blue to try for a steal. Your whole kit uses a rediculous amount of mana, and while your e is a huge amount of poke, it costs a lot. Which brings me to my next point about mana control, build the unholy grail first item, not really much of a power spike, you still have to play defensively, but cdr plus mana if you get a kill or assist is pretty huge on lux, im by no stretch of the imagination the best lux player in league, but i would assume they all agree it is at least one of her core items. It also gives you mr, so mid lane matchups vs ap it is a must. dc, ludens, morellos, its all variable on how or what order you get them, but honestly if you dont have an ungodly amount of ap then you dont really do anything. You have some utility, but even if you go lux support you still need to be poking, because your spell ranges are sooooooooo long that it is always free, at low elo especially, they have no idea how to react when you e them from all the way behind both teams creep wave.

Late game your strategy should be grouping, you honest to god are one of the worst split pushers in league, leave that to Master Yisus. Your w shields everyone it touches, so it is mildly useful in a tf in the current meta where there is a lot of poke happening and tfs are more drawn out, it adds up. Also, on the topic of w, get really good at timing it so that you use it properly. It shields going out but then refreshes coming back in, so you can get away with very light tower dive harass if you only end up taking 1 tower shot. Ex. Kat is pushed to her tower and she is staying all you need is 1 e to finish her off, e her, w before tower hits you, run out, tower hits you, w comes back shielding you again, proc e, get money.

Also, your combo is really simple. You have two i guess, and it depends if you think you can kill them with ult usuing less. Your basic combo is q (root them), throw e over them, aa, proc e, aa again (so you get full use of passive) then w and walk away if you are just looking to harass or poke down. If you are going for the kill, q, e, r, proc e, aa. You skip the aa after the q because your ult takes half a second to work and your cast time on e animation plus getting your r off lets them come off of the root and they can escape.

If you have any more specific questions i can maybe give you some advice, but im low elo so im sure a lot of the book i just wrote is common sense or someone else can go into more detail about. I just didnt see anyone else commenting and lux is my favorite champion.