Just a random idea I had after playing all these Tank or AP Shyvana builds I see posted everywhere. Quickblades actually works really well on Shyvana. Twin Bite already reduces it's cooldown with auto attacks plus Quickblades passive makes it feel like you're playing URF. You can also keep your Burnout going through a whole teamfight and not... burn out. (I'm sorry.)

With this build she becomes more of her traditional fighter playstyle surviving on lifesteal. Just be aware that you are squishier than tank builds and have to actively hit things with autos to survive.

The goal of early game is just to farm minions and get your cull's passive gold to get your core faster.
Stay alive as much as you can, you are weak pre-6. Trade where you can, a lot of top laners can just run up and bully you with their overloaded kits ignoring minion damage and possibly killing you.

If you are pushed to your tower, stay safe and take cs where you can't be punished for it.
An example being last hitting far away minions with your Flame Breath and using Twin Bite to secure minions under tower.
Ask for ganks when your jungler can since you can farm under tower pretty reliably.

Another note is that you can line up a Flame Breath last hit to also harrass your lane opponent, making successful gank kills easier for your Jungler.

When you hit level 6, you can try to fight your lane opponent if possible by engaging with your ultimate. Fight within your Dragon Form Flame Breath's AoE and do NOT chase them down unless you are sure you can secure a kill. Your ultimate technically has no cooldown so you can re-engage with ultimate again later. Just auto attack minions when you can to keep Dragon Form up and harrass with your empowered Flame Breath. Remember your ultimate gives you a small chunk of health and has a small knockback you can use to punish greedy dive champs trying to kill you under turret.

Try to avoid full on 5 v 5 fights unless you snowballed really hard or the enemy has very little crowd control. In the end, you're a lifesteal Shyvana, a really great split-pusher and brawler. If you must fight in an unfavorable position, then use your ultimate away from the enemy team and punish them for grouping with your empowered Flame Breath. Surprisingly it still does decent damage without building AP because of Quickblades passive.

Crit Shyvana is a fun build for those looking for an alternative way to play her.