Hmm...jungle/adc, right?
I can't really give you much for jungle, other than saying that the current meta favors junglers who can gank early and often over those stuck farming. I'll be the first to admit that an Iron 12 monkey could probably outjungle me. >.>
But with ADC, there are 3 current viable paths that are outshining pretty much everything, and it also highly depends on who you're playing.
With Vayne (or with Varus, Kog, or AS focused ADCs) I'd run either PTA or Tempo (HoB works too, if you're a more aggressive player) and rush either Rageblade or Statikk Shiv. Those items give you the strongest early game damage, and with tanks (particularly tank supports) being less popular, a Bork rush is sort of irrelevant, so it can wait in most matchups til spot 2 or 3. Most say Guinsoo's is the more consistent, but I like Statikk for it's ability to occasionally net me that kill on that person who lived with nothing by bouncing it off a creep. These are probably the weakest ADCs in the early game, but the most consistent going into late.
With Vayne in particular, the Domination tree can be particularly kind, running HoB, impact, Collection and whatever Hunter you need, with Triumph and CutDown as your background secondaries. This is probably one of the better pages to run if you're going to try for early game fights and trades, as the sudden impact along with your Q and your 3 stack deals a little extra damage than normal, and if your support is kind enough to feed you an early ward with their vision control, you can get some early stacks on Eyeball Collection to end up dealing some surprising damage.
With Crit based champs, you probably already know the go-to is StormRazor into IE, focusing on consistently dealing the max damage possible, as early as possible. Jhin in particular loves this, but so does Caitlyn, and funnily enough, Lucian (W, SR+passive/E, SR+passive/Q, SR+passive) because even though it makes him feel slightly more clunky rushing stormrazor, it massively boosts his max damage output from a very early point. I will say, a lot of Lucian players don't go SR+IE, they just buy SR, then follow my next build as they take an early lead, before eventually trading off SR for something more usable in his late game. I like running Footwork on these guys, but I've seen a couple of tempo games on them that have gone pretty well, especially with Jhin players since it gives him a huge damage boost on about half of his shots consistently. These are probably the best early game champs in the bot lane, but they're also the most rigid and predictable, and if you can't snowball it to late, they can struggle really hard in the midgame.
Caster "marksmen" (screw that title, they're ranged AD Burst casters, not ADCs. >.>) are usually apt to rush either Essence Reaver, Sheen into either TriForce or Gauntlet, or (very rarely) a Death's Dance (I guess so they can still live a prolonged fight while they wait on cooldowns? I never really did get that one...) with A much larger Variety of keystones (I've seen Klepto, Glacial, Footwork, Comet, Elec and Harvest all run pretty smoothly for these guys.) Despite their adaptability, a lot of these guys are very strong mid game, and not so strong late.