I assume you play on Xbox one and have a Windows PC and are looking not to spend extra money.
To start of write your script, then record you audio, (I'd recommend using audacity as software it's free) . Now create a custom game this is where you do your body acting (moving your people about and head bobbing) after you do what you want to do go into theater mode, this is were you can do your recording, theater mode allows you to get creative camera angles and remove HUD. Use Game DVR to recorded your shots (you can go into capture settings on Xbox one to change quality of capture). Now you need to go to your windows 10 PC, open the Xbox app then go to captures and download your clips. Next comes editing this is were you add voices and put your clips together (I recommend Shortcut movie maker its free), Once you export your project you will be done
Lower your weapons when your characters are talking, look this up on YouTube for your respective game
Spend time writing scripts and DRAW STORY BOARDS, I feel like I ignored this when I first started and I show this in Red Squad Season 1 (My first machinima series).
Find friends to voice act ( I'm still struggling with this one)
Choose your game mode carefully (I use a custom game mode)
chose maps wisely, don't just place your machinima on any map find the perfect one then edit it in forge.
Use Pan Cam this allows you to get really cool shots ( Google it to find out how to do it) Sadly it doesn't work in MCC
Use a spartan as a camera - this seams weird as there is theater mode as it allows you to create unique shots and keep the camera height consistent
speaking of unique shots, be creative use creative methods to create creative shots. An examples of which includes; placing the Spartan camera on top of a scorpions barrel and using is as a planning tool.
Be creative when editing external assets into your machinima, in the case of machinima editing in external assets can improve a machinima dramatically with little need for expensive gear (I was offal at this when I first started in Red squad season 1 but my editing has greatly improved in season 2)
Use forge smartly, alot of people forget that halo is really unique for having a tool such as forge on a console game use it to create cool effects
Add external sounds. Good sound design can make r brake a machinima be smart when adding music, sound effects and audio clips
Thanks for reading all the way through, I'm sorry if this wasn't helpfull. I would recommend checking out Red squad season 1 not just because I made it but because there is an obvious learning curve through out the season and you could pick up tips on what not to do from early episodes and what to do from later episodes.