At first, install and pre-configure your modifications (with Nexus Mod Manager, Wrye Bash, manual install... whatever suits you).

Then start Skyrim SKSE loader and hopefully you get to main menu without crashing!

Next, open up developer console while you're at the game main menu. To open the developer console, press ~ key on english keyboard or § on finnish keyboard. If you use something else, the key is usually at the left of number 1 key. When in doubt, press all keys or search the internet for the key for your keyboard. Maybe UESP.net console commands tutorial[uesp.net] will help you.

Type following to the developer console while you're at the game main menu:
Press Enter-key after you have typed the command to execute it.

Game loads up and hopefully you will appear at the Riverwood without crashing. So far, so good!

Wait for a moment for all modifications to run their startup scripts, SkyUI MCM to configure menus and so on. This will take about 10-15 seconds.

Then let's fly! Open up developer console again and type following:


Now you can fly around the Skyrim by using THE SPRINT BUTTON and see how long your game will last until crashing. You should fly near the ground so all textures and objects are loaded in the memory. If your speed is too slow, use larger speedmult value.

If you want to test new places which modifications added, you could use "tmm 1" developer console command which shows all map markers.

Note: You will get occasional lag as the game will load up resources from the disk drive. This is normal.

At some point, your game will most likely crash. You can't do nothing about it. More important is when the crash happens and are you satisfied how much game resources you have tested. You decide what's enough for you.

For example, you may decide that on your current particular mod setup you'll load all areas from Riverwood to Winterhold, then to Solitude, Markarth, Riften and back at Whiterun. During this trip most of NPC spawners (if properly configured) will fill spawn points with new NPCs and you will load up plenty of texture resources. Or maybe you may want to see how your game works when you move forth and back between Rorikstead and Whiterun.

If game seems to be stable for a long time and then suddenly crash, you could try to remove large texture packs (if you have installed such game crashers:-). Skyrim patch added support for 3/4GB memory usage, but the game engine is designed for technically limited game consoles (i.e. Playstation and xbox). As with Oblivion and Fallout, the game engine will die at the some point when it runs out of texture memory. There are user developed mods to circumvent crashes which come from resource loading, but before rushing to get those remember this: game wants to crash because something fatal happened.

If game crashes nearly instantly, it's usually because you have issues with installed modification. Unload all mods and add them back gradually until you will find the culprit.

It's somewhat easier if you copy&paste code you want to use (e.g. paint all of it with mouse and press Control+C, then open text editor and press Control+V) and save it as the batch file. You can add new text document to Skyrim directory, it's under Steam/Steamapps/common/skyrim. You know you're looking at right place when there is file named as Skyrim.exe. Name this text document as speedrun.txt. Paste following code into it:

Be sure that you save this file as text file! Notepad++ is good free text editor if you need one.

You might ask why not add that "coc Riverwood"-part. Well, that's because you can't add attributes for your player character before your character exist in the game.

How to use this? Start at Riverwood, open the developer console and type following including quote-marks:

You may check also mods on TES5Edit for conflicts and bad edits. However, these usually won't cause crashes, but are more related how the modification will play with other modifications. If you're able to pinpoint a problematic object on mod, TES5Edit or official Creation Kit might help you to cut those parts out.

About console commands, startquest ModQuest and movetoqt might help you to go through mod questline in linear fashion and setstage to skip some quest stages. These will of course spoil the quest plot if you haven't played the modification before.

Enabling Papyrus log in Skyrim.ini, at the section [Papyrus], might help in some cases when you deal with complicated script issues. It's log as its name says, it records only events from the past. When your game crashes, that part of the script is usually not saved into log.

Certain spawners are even more problematic as they might spawn broken items or NPCs (or monsters) only at high player level. Using console commands like player.advskill or advlevel will level your character up for testing, but again, this includes very much guesswork.

Doing research on internet might help you initially choose the mods which are stable. However, many sites (even STEP-project) will promote mods which are crashy and users will just use them. Best way is to test them by yourself and keep in mind that certain crashes will happen only when you tax the game engine to it's limits.

Safe way to play is to keep your mod list short and sweet, using only modifications which you can't live without. That was the heart of the advice I gave before, ultimately only you know what modifications you need and what is your tolerance level for the eventuality of crashing.

However, methods I described on this paragraph are time-consuming methods, unless you really know what you're looking for. There is no other practical quick testing method than fire the game up and see what happens. If the mod is prone to crash, you will catch those mods with stress testing like described above. All other modification related problems and crashes will emerge in their time, during your gameplay.

Anyways, that's all folks. Thanks for reading.

Forget default Windows text editor, get something else to edit Skyrim files. If you don't find anything good, this one is free as beer and you can also use it for coding:
Notepad++: http://notepad-plus-plus.org

Editing tools:
TES5Edit: http://www.nexusmods.com/skyrim/mods/25859/
Creation Kit is available on Steam: Library->Tools->Creation Kit

I would like to express my thanks to:
Skyrim Modding Community