For some this will be somewhat pedantic, but realize the purpose of this response. OP will be using CAT wire and POE cameras.
First, stay away from coax/analog cameras; CAT 6+ is what you should be looking at.
Determine a central location for all your stuff.
Run CAT 6 everywhere you even might ever want a camera. Run strings as well if you want to be thorough- all to this central location. (A closet, or rack, with available electric.)
POE cameras (Power Over Ethernet) you only run the CAT wire, and power comes across that.
Pick your manufacturer, I've also used Amcrest. All cameras should be 4MP minimum, with an NVR that supports that resolution. If you're going simple; a POE NVR and POE cameras from the same manufacturer. Configuration of the NVR can be time consuming, but if you've used Amcrest cameras with an Amcrest NVR (or whoever) it will likely configure itself to some degree.
I used GW security domes with the Amcrest NVR; all manufacturers conform to ONVIF protocols (whatever they are) so different cameras can work with other recording devices. Don't buy any cameras from GW security without asking me. Most of their stuff stinks, but one dome camera is truly the cat's ***. $160.00 for a 5MP with remote lens, die cast aluminum housing. They have one bullet that's OK, but not stellar.
I have a central system with a POE switch made by Netgear that can handle 8 POE devices (actually 2 of them, both gigabit, as I have another area to service- only one camera on the second.)
I've got all my cameras but one home-runned to my primary POE switch, next to my Internet gateway. The 2 Netgear devices are connected with CAT6+, so a gigabit backbone, with a bit of future safeing.
I configured my Amcrest NVR (connected to the primary switch.) to grab the cameras by IP, the power is fed by the Netgear switches.
Additionally, a remote computer is running Blue Iris software (look it up) and will record motion as does the NVR. I'm not actually using the POE NVR for power, bought it for that but things evolve quickly for me at times.
A problem with the Blue Iris thing is when power fails, I haven't yet figured out how to get the BI software to restart on power return, there's a procedure for that, but I haven't chased it down.
Alternatively, the Amcrest NVR reconnects on power up with no issues.
Oh, and if you're worried about taxing your network, my cameras tell you the bitrate they're transmitting, and most of them say under 4000KiloBits/S (4MB/S, obviously) so on a 10MB (obsolete) net you'd be short with 2 cameras, but a 100MB net (dated) you could cover 25 of them.