UltraDad seems to know the most about that
Seriously though don't trawl the thread just look at the first post and skim down it for the textures. In general the best place to start I would say is:
- Install the Official High-Res DLC (through Steam)
- Install SKSE alpha (which has the memory fix patch built in I believe)
- Install the Unofficial patch/es and Unofficial High-Res DLC patch
- Look at youtube videos and screenshots to help you pick and ENB that you like the look of (this makes the biggest difference to the visuals overall) and get that installed, tweak it if necessary to get good performance
- Then you can start installing graphical mods to your hearts content, stick to installing perhaps 2 or 3 at a time before checking your order or running BOSS then loading up the game and testing
My thinking behind this order is that the ENB has an effect on how the game looks overall, and is also arguably the biggest performance hog, so if you know you want to use one then installing it last is a mistake. You may end up with sub-standard performance and have to start pulling out other mods you already installed, or you may find that some of your mods don't look as good with the ENB turned on.
The absolute minimum you could do would be a few higher res texture replacers, plus an ENB (some of which do make the nights a lot darker) and possibly one of the lighting overhauls (not all ENBs play nicley with these though). I went with the "Serenity" ENB which works well with "ELFX" (Enhanced Lighting and FX) making the interiors and nights very dark (I also then installed "Lanterns of Skyrim" and "Wearable Lanterns" to help balance things out a little).