Flash for obvious reasons.
Ignite is nice to burst someone down, but it's mainly nice early cause late you have enough burst, but because Talon shines in the lategame I don't see Firstblood on Talon as such a big adventage if you compair it vs more early champions.
I personally take cleanse because a big weakness of assassins/glass cannons is that they are focused or cc'ed, when being focused you can just burst the enemy that focuses you, but cc is to op:P. So I take cleans, and 2nd reason in midlane vs alot of mages is it really nice, because alot of mages rely on their cc, think about xerath or a lux that can't hit their skills cause you aren't cc'ed. In teamfights it's really nice for going in first, since it happends that some teams just don't go in while playing for instance sej. So you can just go ham e w q their adc and then ult and if they cc you, you got your cleans.

Talon at lvl 1 is pretty useless, so you mainly just wanna try to farm because trading hardly works vs ranged opponents. At lvl 4 you can trade with enemies, you wanna trade with this combo e w basic q and then just walk away.
Important! you wanna try to use your e to dodge skills so you can easy do your combo and walk away without being punnished alot.
At 6 you can do the same thing but then instead of walking away trying to finish your enemy or just ult and walk away in safety. And most of the time their are low at that point so or they hugg turret.
Then you can do 1 push and roam, or 2 try to reset the lane and kill them because of their mistake of position or their greed for minions/staying in lane.
If they go b you can push with 1 basic and q on the turret and roam or go b aswell since you've pushed so you won't lose any exp.

You mainly wanna roam botlane if you roam.
If you go bot and they are pushing towards your turret you can just walk up to their adc and w then and basic q and if they use their dash just use your e and then basic q and ult and run in front them and wait a bit for your w cooldown and then you can probually finish him off.
If your lane has pushed you can't really gank efficient but you can just on their adc with e and then just w basic q ult, and run away and hope your adc finishes theirs if he isn't dead allready.

If you have any feedback, I'd love to read it because I'm just Silver III and I main Adc but for midlane I main Talon and Velkoz, and jungle Sej and Voli, and bot Twitch, Jinx, Sivir, Leona and Sona. (I suck at toplane >-< but if I must I just play Shyvanna or Trundle, and try to feed)
So if you think I should give you more details perhaps more details about certain matchups (cause I made this around 2 Am and was to sleepy to think about certain matchups)
But if this is good content then I'll make more Guids about one of those champs.
Thnx for reading all of this, and hopefully you've learning something from it.