She was just nerfed, so I wouldn't count on her receiving another one anytime soon, though they may do a numbers tweak. The best advice is to try to put pressure on the lane and gank when her ultimate is down so she doesn't have that extra utility and escape. CC is also a good resource when trying to fight Shyvana. Might want to look into some MR or a way to sustain through the damage that she can put out. Like the rest of the damage dealing top laners that also can tank (Rene, Trundle, Mundo) it's pretty difficult to deal with Shyvana without committing resources.
As far as playing her, itemization really depends on lane matchup (or if you're in the jungle) but due to her percent damage in her kit you really only need to build some health and get tanky to do a great job. I'd recommend a Sunfire, Randuins, Tabi/Merc Treads focus. Possibly get a Wit's End if they are heavy on AP or a Thornmail if they are heavy on AD. Jungle item I'd recommend a Lizard Elder and Mobi Boots.