Dinah couldn't help but chuckle at Selina's insistence that they were just more experienced- not old. Experienced was definitely one way of looking at it.
She smiled, and out of respect for her opponent, gave a slight bow before taking up a relaxed stance, feet shoulder width apart, knees bent, keeping her shoulders loose and her arms up.
They could stand and stare at each other all day- waiting for the other to make the first move. In fact, there were plenty of opponents that Dinah would have been content to wait on for hours or days if necessary. But those were life and death situations (or very heavy, intense training sessions) and not for a friendly spar. Besides, taking a few hit wasn't going to kill either of them.
Dinah hadn't personally fought with Catwoman (or her infamous whip), but she knew several people who had, none of whom seemed to think it was a walk in the park. The fact that her colleagues, some of the best martial artists in Gotham (maybe the world in some cases) though Selina was dangerous was definitely something Dinah took into consideration now.
With two quick steps in, Dinah shot off two quick jabs towards Selina's face- not trying anything more sophisticated than straight boxing for now. She wasn't looking to strike any hits. She was looking to see if Selina would block, dodge or counterattack- how she reacted. That was the key to any strategy.