Here's a little something I probably should have thrown together long ago. Meh. too lazy.

Rule 0:
Read mod descriptions and instructions. Do it. Now! Before you install them

Rule 1:
So you're updating some mods? Read their description and installation instructions. You know how to handle the mod? Read the instructions again! Mods change.

Rule 0,1 addendum.
Read the last 5-10 pages of the respective forum thread. Chances are any known issues have been already mentioned there.

Rule 2:
I crashed!

Read the report/log. Most issues are rather obvious. If not , then post them for somebody else to read. Use spoilers or paste sites.

Dropbox/Mediafire/ect if you really feel the need to touch that huge FML log.

Rule 2a:
There's no report!

There's always at least one log (up to 3). For Mojang launcher/Curse Voice set launcher visibility to keep open.

________________________________________________________________

Now some very common stuff to take note of:

#1
Curse Voice Minecraft plugin is currently broken for custom packs. It's good enough for pre-made modpacks.

It's clearly marked Beta. It installs only the latest file available from an archive and does not filter mods by version. Ergo: it will install wrong version mods.

Either don't use Curse Voice or manually fix it.

#2
-Java 8 is bad for Forge.

No it isn't. Stop listening to all the criers and actually do some research. that issue was fixed in October 2014. All Forge versions past 1217 are pre-patched for Java 8. For earlier versions there's Lex Manos' Legacy Java Fixer.

http://files.minecraftforge.net/LegacyJavaFixer/legacyjavafixer-1.0.jar

#3
-MOAR RAM!

99% issues with modded Minecraft have nothing to do with RAM. NOTHING!

Most of them have everything to do with people not reading instructions. See Rule 0 and 1.

Read the crash report/log. Memory errors are clearly marked. Or have someone read them for you.

#4
-Optifine is bad with mods.

No it isn't. It has some known issues. Most of them have been long since fixed. Always use the latest Optifine.

The only exception right onw is Shader mod for Minecraft 1.8. It won't work well with Optifine D3. Which is clearly marked in the description, see Rule 0,1

#5
-I got a crash like this:

Description: Unexpected error
java.lang.IndexOutOfBoundsException
at java.nio.Buffer.checkIndex(Buffer.java:512)
at java.nio.DirectIntBufferU.get(DirectIntBufferU.java:248)
at net.minecraft.client.renderer.RenderGlobal.func_72712_a(RenderGlobal.java:350)

You've been playing Minecraft 1.8+ with Render Distance set to more then 16. Lower it.

#6
-I got a crash that mentions Capes and/or AuthLib

See #4.

#7
-I got a crash that mentions Splash Screen

See #4. And update Forge.

If that doesn't work, disable the loading screen in splash.properties.

#8
-Shader mod does not work/crashes.

See Rule 0.

-I read and checked everything, honest. I use a Laptop with a real GPU.

Force it to use that GPU for Java by setting up appropriate profiles in Nvidia Control Panel/Catalyst Control Center. Because it won't by default. Blame the fact it is a Laptop.

-I read and checked everything, honest. I use a Mac

Most higher end shader packs don't work on Mac OSX. This includes all versions of SEUS. Blame Apple playing loose with OpenGL implementations (and partially Mojang).


More stuff might be added if I find something annoying showing up excessively often. Might edit this to look nicer when I get over my inherent laziness again.