A face-to-face, one-on-one meeting between President Trump and Putin is a really bad idea.
The USA has some pretty serious issues to hash out with Russia, and we have seen that Trump is ineffective in confronting people face to face.
In his early meeting with the president of Mexico, Trump did not even raise the issue of the wall, in a previous meeting with Putin he meekly accepted Putin's obvious lie that Russia had not meddled in the US election, and in Singapore he let Kim off the hook with vague assurances that Kim has already reneged on.
In short, President Trump is a lot like The Wizard of Oz -- heap big smoke, no fire.
Putin would eat Trump's lunch, then have him for dinner.