Hi Lotta!
great question for your first post. 
Short answer: Reels can be great, but if it is only a reel it really needs a lot of effort to be informative without “wasting time” of the viewer. There is often more effort, time and editing skills required than a straight portfolio. Reels in my opinion should be short and clear as an “introduction”. But in the end not the thing you should mainly focus on.
Long answer:
The most important thing to sell is you. As Torbach said, it should show that you have the knowledge and artistic vision which are searched for.
Here are some pointers on what a good portfolio needs in my opinion:
-
Clear structure
think about how to group your effects that each group can have a common headline. If possible have some sort of quick navigation to these groups. (In my portfolio as TA I had: projects, effects, materials, tools, other projects) -
Visuals
I want to see pictures (moving and stills). Effects should be shown in context and additionally in a test environment. -
Descriptions
Have descriptions on what I am seeing and what you did with it. These should be short tho’ -
Breakdowns
This is not needed for all effects, choose one or two of each group and make a more detailed description with some extra pictures (uv map, 3D program scene, packed textures, or similar)
This will show, that you actually know what you are doing. -
Easy to navigate
This one is a general one. If I have to review 10+ portfolios in a short time frame, I will most likely skip people that make it frustrating to look through their folio (may it be an overkill website or a video that I have skip around too much). Your portfolio should be easy to pull up and navigate to a specific part.
I hope these help
Edit: Here are some more topics about portfolios:
Good luck with your portfolio!