As mentioned before, never put switches, modems or routers in a attic or garage. You want air conditioned space and airflow. A closet is fine but put a louver high up on the door and leave some breathing space around the equipment.
A Central Location is important, because likely one of your devices will be the WiFi router. Router is also important, most nowadays have at best 5 ports (8 if you are lucky). You want a 16 port gigabit capable switch.
So get you a spool of Cat 6 (1000ft), another spool of RG6 Cable and run 2 wires to every possible location you can think of and a run of RG6 to every location you might EVER put a TV. TVs usually have a PS or XBox sitting right next to them, maybe a media player as well, there's 4 connections right there. So for your main TV location I'd do 6 runs. It ***** having to use extra switches everywhere or being forced to use WiFi when you need your setup to run wide open with very little latency. Don't forget each corner of your house for security cameras. So that brings us back to your router/switch setup... Get a 16 port switch that does POE (power over ethernet).
I've used MonoPrice to get cable, ports, plugs, etc.. from in the past, wired my parents house, my sisters house and my girlfriends house with it. Better to have a unused port/cable sitting there than needing to pull cables, yet AGAIN, or to plug a 4 port switch w/yet ANOTHER wall wart sucking ac/dc power off your meter 24x7. They add up. I think my cost to do a entire 3 bedroom house was around $400 in materials and my time. Things are a lot cheaper now. Cat 6 Keystone is $1.20, fully shielded ones are only .25 more... Thats cheap. It's all China stuff, even the stuff from Home Depot and Lowes.
We ran everything to a central closet, put a 3 Gang Box in, 3 Gang Decor face plate with 16 ports on it. We even color coded some of the jacks. We had a separate 1 Gang face plate with a 2 port plate for the incoming cable and incoming POTS (plain old telephone service). Every room had at least a 1 Gang/2 port face plate installed. And everything was Cat 6. Fully Gigabit Ethernet ready. Just not worth messing with installing Cat 5 stuff anymore. Sure some pulls were unused, but we didn't ever need to plug a extra switch in to hook up a 2nd device.
Here's a quick picture for reference. Dragged a few items out from the box sitting here ready to go into my new (old) house. I started out with a less expensive tester, but kept looking and found a good Craigslist deal on a Fluke CableIQ ($300/$1200+ retail 8 yrs ago at that time) after the parents house and haven't looked back. Even the cheap ones will get you a quick good/bad reading. The tester, wire cutters, fish tape, drywall saw, a good punch down tool for the jacks, and a couple other common tools is all that's needed to get professional results. And all of our wiring runs were hidden in the wall cavity except for between the devices sitting on the shelf or the ones we could mount directly on the wall. How clean you do it is up to you. Helps if the walls are accessible from the attic for the runs, outside walls are a pain. Also allows you to pull all the old 4 conductor POTS wire off from around your house and old RG59/RG6 cable too. Really cleans up the outside. Gets everything into the Attic or Basement (wherever your wires run internally).
