My advice would be
1. Definitely go preinstalled,way less hassle because everything "just works"
2. Avoid dual booting if at all possible, or have windows on a completely
separate machine from your gnu/linux one.
3. Definitely run a FSF recommended distro or at worst, Debian. Why? Because
the other distros don't really care much for freedom.
4. For privacy Parabola maintains a repo of privacy conscious free software.
I don't think I've come across that on trisquel, but either way a side effect
of free software is that it doesn't spy on you by design. 10/10 good stuff.
5. Absolutely avoid Skype. Privacy nightmare (you basically have Microsoft
listening in to everything you say, do or film). Check out Riot, Ring or
qTox.
6. If you must use Windows on your machine that is otherwise free software VM
it in QEMU.
