Before installing the mods, there are a few thing that needs to be setup

1 -
If you haven't already, sign up at the Nexus. (LINK)
It's free, and it takes 2 minutes.

2 - Downloading and install NexusModManager (NMM) (LINK) *Install descriptions are found at the Nexus page if needed.

3 - Download and install "Oblivion Script Extender" (FOSE). (LINK) If you are running Fallout via Steam, you need to download both the main FOSE file (fose_v1_2_beta2.7z), and the latest loader (fose_loader.7z). If you don't run Fallout 3 via Steam, you just need fose_v1_2_beta2.7z. Unpack the file(s) into the Fallout 3 game directory. Installing FOSE is absolutely necessary, as most mods simply will NOT work without it.

4 - Rename the launcher (For the Steam version of Fallout 3 ONLY) Go the the Fallout 3 game folder and rename "FalloutLauncher.exe" to "FalloutLauncher.exe.backup". Then rename "fose_loader.exe" to "FalloutLauncher.exe".

5A - (This ONLY applies to 64bit OS's) - Download 4GB Memory Patch. (LINK) *I don't know if there is a way to increase application memory on a 32 OS. Google is my best advise. However, this patch is not necessary for using the F3BP ENB settings or the essential mods. BUT, if you want to install the complete setup for high end systems, this IS necessary for stability.
Unpack the file anywhere you like an run it. Select "Fallout3.exe", and click OK. If you get a "patch successfully applied" message, you are all done. If you get an error message instead, don't worry. This happens if the OS protects .exe files from being manipulated by other applications. Windows 7 is notorious for this. The workaround is fortunately very easy. Rename "Fallout3.exe" to e.g. "Fallout3.exe.back" and run the 4GB Memory Patch again. Now select and patch the "Fallout3.exe.back" file instead. After the "patch successfully applied" message has shown, close the patcher and rename the file back to "Fallout3.exe" - That's it. Windows "super" protection bypassed.
*If your firewall or Antivirus complains about the patching, just ignore. The patch is 100% safe. All it does is change a flag for memory usage.
5B - Now patch "FalloutLauncher.exe" the same way.

6 - Launch NMM
At the very first startup, NMM will search for your game(s). Let it finish, or cancel the auto-search and type in the Fallout 3 folder-path manually. Then you will be asked where to store the mod files. Choose any place you like.

7 - Make some coffee. Downloading and installing all the mods will take a while, so be prepared. However, at the end you will get the result of several weeks worth of tweaking and testing.

When ready
Proceed to the Mod-List



Curious if the results are worth the effort?  - Here are some before/after screenshots.
*As taking "before" screenshots would require me to uninstall every single mods again, I found some screenshots on Google instead. I then took a similar shot with the F3BP ENB settings enabled and all mods added. It's difficult to match the exact same shot with location and time of day, but these should be good enough to give an idea.

ENB 1.81 Screenshots

                      BEFORE                                             AFTER                                                      BEFORE                                              AFTER                      .