This is where all Garry's Mod video makers start - the planning process. Without a good plan, the video won't exactly be well-thought out and the users at YouTube wouldn't exactly approve for the most part. Make sure that you make notes of what you want your video to be about, exactly which characters are included, and what happens in order. This can give you a significant advantage when it comes to actually making it.
Don't rush this process though - think carefully. If you want the audience to be enthralled by your video, you need to make sure you have a fairly decent idea of what to do. Otherwise it'll just end up as a mess. And we don't want that to happen, right?

With the planning complete, it's time to load G-Mod up and get started! But don't make it straight away if you are not familiar with the setup. Take some time to get used to controls. Plus, make sure you make use of these tools:

The camera tool: This is pretty much obligatory when it comes to making Garry's Mod videos. By keeping the camera focused on one character or piece of scenery and moving the item accordingly, the end result provides smooth animation, on the chance that you've done some earlier practice beforehand.

The No-Collide Tool: This can be pretty useful for making things clip together. For example, if you want a Spy holding a Pistol, you could use the tool to make things clip together. Alternatively, you could also use the Weld Tool to stick objects together.

The Bone Merger Tool: In terms of Team Fortress 2-related stuff, this is quite handy. The idea is that you can select a ragdoll, then select any items to equip on said ragdoll. Although it doesn't work on some ragdolls, it can prove to be quite useful in making characters and personas (more on that later).

These are only a few examples, and there are a lot more out there that can help you. These three, however, are quite useful when it comes to making videos.

This is where the REAL part of video making begins. Before you get started on recording, set everything up beforehand - make sure that the scenery and props are in the correct place and the ragdolls are in the correct position. That way, they're there when you begin making the video, and you won't have to mess around with it later.

Setting up before you take the screenshots for the movie can be helpful, and these are a few examples that I have put together myself (which are also in my screenshots section):

Time to make that video! But you might want to consider the following points:

-Have a good video making software: That's right - for the most part, Windows Movie Maker will NOT cut the cheese. Sony Vegas software is one of the greatest options to use for making Garry's Mod videos, albeit its enourmous price tag.

-Have a good recording device: A simple recording device, such as FRAPS, can also be used as part of your movie. This can be used in any instance of your movie where animation can't be used, for example, throwing a body off a cliff.

-Make sure you have good animation - If you're not sure how to do this, be sure to look at some video tutorials for elements such as movement and lip sync. GmodExpo's and Dr. Face's in particular.

With that said, you can begin to make your movie as you please. Be sure to use the camera tool to ensure a smooth finish!

With your movie created, it's time to place the screenshots together to make it look good. Again, WMV is NOT recommended for this process, with Sony Vegas being a favourable program. Make sure that the animation is fairly smooth - make them last at least 1 frame each, with half-frames or longer-lasting frames when necessary. That way, the balance will be equal and it will not be too fast nor too slow.
Another key factor is sound. This can be tricky. Use either the internet to search for sounds, or in the case of TF2, use GCFScape to extract the soundfiles. That way, they'll sound clean and will be ready for use.
One last factor - music. Find some appropriate soundtracks. I won't go into too much detail about this, as you most likely have a different taste of music to me. YouTube is your friend, so scout around until you find something good.

With that said, get editing!

Once you have got the basic structure of your video done, music, speech and all, replay it a couple of times. If you are happy with it, render it, but if you are not, be sure to make finishing touches and add necessary tweaks. Now you can render your video!
Assuming you have a YouTube account, you can then upload what you have made, and wait for views and comments to come in. If it gains lots of likes and positive criticism, then you've done great! But don't be afraid to listen to criticism for areas to improve.

Congratulations! You have successfully created your first (or depending on when you've started, Xth) Gmod video!
Why not take a few minutes to look at some other helpful tips in this guide?

What do all of these screenshots have in common? If you pay close enough attention, they actually have some significant effects that can really enhance the scene. These can be found in the Post-Process tab at the top of the menu (when you press and hold down Q)
Have a play around with what you can find, and see if you can use these effects to help you. Don't overdo them, though!

While not strictly necessary, it may be an idea to create a persona (a character who represents you, the user) to use as a trending theme in your videos. This seems to be more apparant in TF2 parodies, although it is not limited to this. Here are a few examples of Gmod Personas:

• ARL3 (me): RED Sniper with Texas Ten Gallon, Cozy Camper and Teufort Tooth Kickers. You may have seen him a couple of times throughout this guide.
  
• GmodExpo: BLU Heavy with Soldier's Stash and Summer Shades (and possibly Teddy Roosevelt)
  
• Dr. Face/69Starmix96: RED Sniper with Larrakin Robin
  And so on.
  
  Be sure to make your persona unique. Try a combination that no-one may have tried before. Experiment with characters and items (and use the Bone Merger tool if you have it) to make a combination for your personal character.

If you make a video with a certain character or theme, and it receives a generally positive reception, it means that it appeals best to the audience. As a result, you could use said theme or character in another, or several, videos, be it cameos or full appearances. Be sure to leave the original video on for a while beforehand though - don't rush headlong into it and post its sequel immediately. Wait for a while before doing so.
Trending themes can mostly occur through Gmod collabs, for example Kugawattan's Golden Sword Collab:

I hope that this guide has helped you with making Garry's Mod videos!

Feel free to leave behind a comment to say whether you found it useful or not, or what I could improve on!

Thank you for taking time to read this guide, and I hope it has helped you!

-ARL3