Does anyone have any tips on how to play Diana either mid or jungle, or even as a top laner? I've been thinking about trying her out for a while now. I usually play tanks in the top lane but I want to try and play mid and jungle a bit more.
Diana is my favorite champion and my main mid laner. What tips are you asking specifically? I play her mid mainly. I start with Doran's Blade, 2 health pots and a trinket. I start with her W, her shield, as it can negate early poke and helps you farm, but don't spam it as she can be mana hungry early. I get my Q second then go 2 in Q and 2 in W before getting my E at level 5 then my R at 6 of course. I poke with my Q a good bit to annoy my enemy laner but not enough to be manaless, and farm as well as I can. If they try to trade with me I will trade with them, then retreat. Diana is a late gamer, she has weak early power but once she hits 6 and onward she gets hella strong. Once I hit 6, and they haven't backed, they should be missing some health from my poke so I usually try to go in with a combo. I hit my Q. hit RWE and a second R if they haven't flashed out, and ignite if I need too. My build is usually 
and use my last slot for a defensive item, but the build can tend to change depending on each match and who I'm up against.
I recently heard a tip where the build to start out with on her is 
and follow up with Luden's and whatever else, but I haven't tried that yet. My build usually works well for me.
If you have any other questions feel free to ask.
Save your vacuum for when people are out of auto range. Essentially. When you feel you have the damage to kill, it's Q+Ult+shield. AA them and follow them to get your passive cleave. Don't use your second ult too soon. If they try to flash or use an escape then you just vacuum them back. The second ult is kind of like insurance. If you didn't have enough damage and they flash or happen to start getting away anyways. NOW ult again and ignite if you have it. I don't play a lot of Diana myself, but this is how I see my buddy get like 80% of his kills mid-lane. He was plat last season and Diana is his main carry champ.
I would say learn to keep track of your passive, it's a lot of extra damage. And used properly it can really help you farm (If your Q hits the minion wave to leave the casters at low HP then you have you passive ready to cleave them all in one AA) Having the passive ready before you go in for a trade will be worth the practice. Trust me.
To land q on juky opponents who understand how the skill shot works, throw some oddballs in: get a feel for the curve and line it up so if they stop moving to where they think you're aiming, they'll be hit with the long part of the skill shot. do this by aiming it ahead and to the left side of where diana is facing. it limits your range but ups your probability. if you're jungling, screw litch bane in favor of runeglaive and consider getting something for mana regen, otherwise you'll have some serious trouble with engaging, then not being able to do anything to catch out. additionally cdr and attack speed are beneficial, as your passive does some serious damage if your cooldowns are off except for the ult which when you dont have q should only be used for a straggler execute you know you'll regret.
I typically build 
(or
) 
(or 
) and boots of choice depending on the circumstances. when I jungle. the runeglaive uses spellblade which cuts the need for litch bane. the tooth offers additional attack speed that has synergy with her passive and adds 20 cdr plus 80 ap which also helps her passive some. because you're heading into the mid game from there, you need some tankyness so you're not suiciding all the time, so I build a giants belt into the crystal scepter to add health, 80ap and a slow to make up for if I haven't bought boots yet. from there you can branch out, getting resistances and long term combination items like roa archangel's or majai's, ability power like hourglass, deathcap or ludens or my personal favorite magic penetration which I build torment if I'm not satisfied with my tankyness, void staff if I feel like the ap isnt enough but they built resistences and if they have an ap dependent comp abyssal. finally after Im sure to build boots to the situation, I like to get mana regen from unholy or morello, so I can dish out in a fight as long as possible in late mid game. and always, on my first or second full back, I buy crystalline flask and sell it by the time I get crystal scepter. because it's good sustain and she needs mana like no one's business if you're clearing fast enough.
as for masteries, be sure to get the spell/blade weaving combo, attack speed, and bladed armor. my runepage hasn't been locked down yet, but armor yellows and ap quints are highly advised and flat cooldown blues are reasonable for the early-game cooldown boost.
if you follow this in a lower elo and go through your jungle until level 6 before ganking, you'll become a decently strong objective blazing lunari. or you'll just suck. Idunno, I don't play ranked.
tl;dr: either go all ap or get some health for a forgiving moment.
