My simple guide on how to build Shyvana, this is my own build but some bits taken were taken from Phreaks spotlight but changed to be nothing but pure DPS.

9x Greater Mark of Desolation
9x Greater Seal of Resilience
9x Greater Glyph of Shielding
3x Greater Quintessence of Desolation

Shyvana is pretty squishy early game, having both defensive runes will help you pick up a few kills early game allowing you to dominate later game with more items and lots of armour pen

14/0/16
Mastering both Ignite and Flash

Item build above, If you're lucky enough to build up to trinity force and the game is still going.

Sell Wriggles' Lantern and buy Stark's Fervour
and sell Wit's End for Madred's Bloodrazor

You should now be 2-3 shotting every non-tank champ :)

Max Burnout ASAP for speed and aoe damage to help farm gold from minions
1 point in Twin bite at level 2 and 1 point in Flame Breath at 4
then max Twin bite followed by Flame Breath
And Ulti when ever possible obviously ;)

Ignite and Flash are both great choices

A good use for flash is an enemy champion is near your turret you can flash behind and quickly use Dragon's Decent to push them towards the turret to help you pick up an easy kill.

Here are some kills of previous games the last couple of days.