If built right, Lux can be a very bursty champion, and she is great semi early on in the game if she is able to pick up enough Ability Power early on.

In my rune page, I grab

Greater Seal of Replenishment so that I can last longer in the lane without having to recall since I dont get Clarity. With these mana regen seals and my Doran's Ring, I can win my lane without having to recall because I ran out of mana.
Greater Glyph of Cooldown Reduction runes for cooldown reduction.. I think these are nice to have. Allowing you to use your Light Binding+ Lucent Singularity+ Finales Funkeln combo more often, mostly for my ult though.
Greater Mark of Magic Penetration runes are nice too, for obvious reasons, but they usually are able to go through peoples magic resist unless they are building it.

The best part of my runes are my Greater Quintessence of Ability Power. With these and Doran's Ring, give you a great early game burst in ability power. Lux is very capable of getting first blood even though some people say she is weak early on.

Ability Sequence
1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18

I see a lot of different skill sequences for Lux. Some people start with Light Binding. You can do this especially if your are invading the enemy jungle, but I normally grab my Lucent of Singularity for the damage. When I level up I get my Light Binding, then upgrade Lucent of Singularity again because this is your main source of damage before you get your ultimate. Always max your ult when you can, at lvl's 6-11-16. Max your E and then get Prismatic Barrier if you want to be more supporty, or Light Binding to do a little bit more damage.

Now to the actual explaining of my item pick. I see a lot of lux's start off with Boots, or a saphire crystal and later get Tear of the Goddess, but I really like Doran's Ring.

While they nerfed the life on it in a patch, it still gives you 80 hp. The early Ability power is nice too, but the biggest bonus of it is the mana regen. With the extra 5 mana regen and your runes, you will be able to survive mid lane. After Doran's Ring, I still dont get Boots. Some people find this weird, but with Lux Light Binding, ability power is more important that speed. She can get away from almost anyone without boots with her bind. Sometimes it's fun having people chase you. Bind them and E them then auto attack them, and then you will be the one chasing them.

Kages Lucky pick is a great early on item. It gives you ability Power and more money. Then I do get tier one boots,

Then move on to another Dorans ring.

Now i am not going to spam Doran's Ring because two is enoughmana regen before you get morellos evil tome. Next I try to rush Ability power. I get Sorcerors Shoes.

Then I rush ability power with Rabadons Deathcap

Lich Bane is a must have for lux.

It makes her combo soooo much better. Making her a whole lot more bursty. Then i grab morellos evil tome for the cooldown reduction and the mana regen and of course the AP

Then Zhonyas hourglass for when you get yourself into a pickle.

Finally I get void staff for even more AP and some magic pen.

A lot of people playing as Lux get Clarity. This is a big NO. With the right Runes and Doran's Ring, this is unnecessary. Never get Clarity.

I get Flash. Flash is the best spell in the game. Great escape, great attack, great everything.

I also get Ignite. After you use your combo of Light Binding+ Lucent Singularity+ Finale Funklyn throwing in a basic attack to activate your Illumination, the enemy should be dead, but sometimes they persist. This is when you throw in your Ignite (or sometimes before using your ult if you dont think you ult will entirely kill them because most of the time they will be out of range by the time you use your ult)

Lux is a great mid. She can support, but she doesnt have to. She can do some damage on her own.

When midding as her, try to throw your Lucent Singularity behind the enemy champ so that they run into it, or place it in a spot they have to run through to get away. Her E also slows the enemy, so if they are running, throw it infront of them and explode as the are about to get out of it so that they are slowed for the longest possible time. This sometimes messes up because they might use Flash to get out before you explode it and you lose a kill. Try not to use your Light Binding often. This is your protection, and I dont like seeing Lux's die because their protection is on cooldown. If the enemy team does not have a jungler you can use it more often, but still be wary. She is great at last hitting. Throw your E on a group of 3 or more minions and wait for them to lose some of their health then explode it. Near the end of the game, your E can insta kill minions, but earlier you sometimes have to auto attack to trigger your passive Illumination.

Her combo. When your enemy champion get to half health or so and you feel confident that you wont get ganked, throw your Light Binding and instantly your Lucent Singularity. Auto attack, then explode your Lucent Singularity and then Ignite, and use Finale Funklyn. You should be able to do all these things while they are stunned. If you dont miss, they should be dead. If not, auto attack to trigger your passive again, and then they should be dead.

. Some people think Prismatic Barrier is useless if you aren't supporting. This is false. I have been saved by this many times. It is great against Ignite. It shields Lux twice and should be able to save your from an Ignite. Later in team fights, you dont miss, you should be able to save your team mates from time to time. The more AP you have, the more it shields.