It is a big plus to check in, if possible. Letting the Admissions Team know that you're there to visit and see the campus as 'self-guided' - is a plus in their book. *After the tour, you can determine the names of the admissions rep for your area -- work to connect with them after the tour(s) with a 'thank you' note and to ask any questions that you may have (even if it's simply, "What are next steps?".
If self-guided, be sure to pick up a map of the campus and focus on the places that mean the most to you and your future -- where will you spend your time? What shouldn't you miss? Those places will primarily be:
A dining hall
A freshman dorm (if you can gain access)
Buildings of Anticipated Major/Minor(s)
And then see places that are more fun/entertaining in nature -- common areas, student center, etc.
We stress that while you're walking - be it self-guided or formal - to (1) earnestly see if you can picture yourself in that spot for four years, and (2) come up with questions that you may have to then follow up on.
Questions on campus tours? The college process as a whole? Do not hesitate to reach out to us!