There are various ways to address this, but I've learned very early on that it's annoying and monotonous for the reader (or at least me, personally) when I'm reading a conversation with excessive 'he said/she said'. I go about it a different way.
>A somewhat middle-aged man talking to a young woman
"You got daddy issues, or somethin'?" The deep, gravelly voice had a smile in it, reflected by the one that shone at her across the diner's table.
"Still chasing young skirts?" In both word and face, the higher pitched voice replied with an equally amused grin. The conversation had been ongoing for coming up on an hour, they weren't sure how many cups of coffees they'd had but needless to say the two were very much enjoying one another's company.
"Alright, alright, easy now. So you were saying about your co-worker-?"
"Yeah, Sandy! So she tried the same site, right?" Eager to continue the story, he could barely finish the final syllable. "The guy's picture turned out to be, like, 20 years old! Mirror on top, salt and pepper on the sides... mostly salt... and maybe half a dozen teeth with none in the front." The man across from her, to be fair with a little bit of 'salt and pepper' himself, mostly pepper, was already bucking his head back however attempting to stifle his laughter with a large, calloused hand over his mouth. He could suddenly smell the cologne he'd dabbed on his face and the back of his neck before leaving the house an hour and a half ago.
"Y'know, yer pretty HOT fer an ol' guy..."
"Ahhhhh, go on!" Nearly spilling some of his drink on the bar they'd been drinking the night away at, he leaned back in disbelief, then put on a show of an overdramatic woman in a B-movie acting overly embarrassed, the backs of his fingers coming to the edges of his jaw. "You'll make me BLUSH!"
To this, his date for the evening, or rather, now well into the night, roared out with slightly cackled laughter, but to his ears charming none the less, and he adored being able to make her laugh so. He could feel the years turning back with each bounce to her chest as her head hung back in revelry. Though she couldn't see his gaze on her bosom, she knew it were there, having gotten used to it in their short time together, and somehow enjoyed being so clearly desired.
>End
Alright, so there's an example. Describe the voice as deep or high-pitched, say 'man' or 'woman', specify 'young' or 'old'. The occasional he or she is ok but don't let it become monotonous. Also, once you've got the conversation going, you could forgo description of who's speaking altogether. When it's established that it's only two people talking, then just have them talk, and leave description out of it unless something changes or someone does something.
If you really can't think of anything to do but put 'he said' or 'she said', then this...