After fighting with Hammer to make maps for the past few weeks, I've been able to gather a lot of knowledge that wasn't covered in any of the tutorials I've been able to find so far. So, I wanted to make a list of all the things I wish I knew before I even got into Hammer. Being that I am a beginner, I'm sure there's other stuff that more advanced users can add, and I'll be sure to edit this post with new suggestions. Cubemaps must be placed at a players viewheight Texture every brush with nodraw when blocking out the map Use "3D Flat" in the camera view if it's too hard on your eyes When you do begin to detail, texture only faces a player will see Props with origins located outside the skybox will be recognized as a leak Never make a structure that appeals to a single class (such as a designated sniper hut) If Hammer is open, TF2 will fail to update In my case, Steam will claim that the update files are corrupt Update your map filename between playtests If you and your tester have different map versions with the same filename, the game will throw an error Don't check "run game on compile" when solo testing your map Instead, leave your game open, and type "map [name]" in the console You will no longer have to restart your game between changes When detailing, use "alt + m2" to align textures Select a face with m1, use m2 on an adjacent face while holding alt to automatically "stitch" the textures func_detail should be used when a brush doesn't significantly block a player's view Convert brushes to func_detail by clicking "To Entity" Convert them back by clicking "To World" Keep displacements to 3rd power, 2nd power can be suitable for small details Grid size should be kept between 16 and 64 units when blocking out areas Static player models and spawn entities can be used as references for scale Test with more than one class, or at least one with close to 100% speed For quick iterations, a sloppy 2D skybox around your map will suffice Use the cordon tool to accomplish this more easily Displacements and entities will not seal leaks "Fast" compiles are good for quick solo tests, but never for playtests or published releases Ensure that your props are usable for their physics category Many props are not designated for use as prop_physics or prop_static Get into the habit of saving manually after substantial changes Autosave can work, but is sometimes unreliable and can save at inopportune times That's all I have for now. Please let me know if any of this information is incorrect or encourages bad practice - I know I still have a lot to learn. Hope this helps at least a few aspiring mappers.