I came here to address exactly this. I have studied a few different forms of meditation (including partner meditations, and walking meditations), though none of them in depth. For me, "thinking of nothing" is always the hardest part.

I have been offered a few tricks that I have found helpful:

• If a thought enters, picture a sky full of clouds, and let that thought drift away with the wind.
• Similarly, you can envision a stream or a river and let your thoughts float downstream.
• Sometimes, if they are important thoughts, I put them in a (visualized) box at my feet so I can return to them when I'm done meditating.
• If visualizations are not your thing, then focus on the sensation of the breath coming and leaving through your nose. Focus on what it feels like for the air to pass through your nostrils, both in and out.

Often, the way meditation is spoken about can often seem overwhelming. But there are so many ways to get the benefit without the struggle. Hopefully you'll find your "right way"!