If you know about computers, turn it off.

Never use this function to use another program while game is on.
If you have 2 screens and the game's not correctly opened in full screen, clic on the other screen, then clic on the icon of the game to get the game back in full screen mode.

You may experience strange crashes, anyway.

Be patient. It's an euphemism.

When you host a game, make sure your workshop maps got their blue icons.
If not quit and rehost. You'll get the icons and all your maps fast for uploading to others.

Test all maps, you'll find some stable ones.

A correct amount of medium maps. Prefer this size for fluent games.

Don't use buildings with spawn timer, except villages hotels and lions.
On the contrary you can place units.

Don't use treasures = crash.

Make sure that your castle got its all square white lines around the flag.

Don't make too much ai.

Keep different saved versions of your map. Coz map editor crash like a s...

Again, prefer a medium map for all kind of player's pc.

I don't know technically, but the fan cooler of my graphic card suffers in this game.
You need a good comp. Strong familial or Gamer.

Don't produce wagons for crossbowmen, it's a torture for the bandwith.

Check if you can play without trebs and engine towers when you feel in a laggy day.

And have fun.