It's hard to know what makes a great showreel - throw a coin in the air and it'll land on a different opinion. But I've probably watched 1000s and so I've got a few tips from personal experience which you may find useful to know
Get to the point!
Simply put; Filmmakers, Casting Directors and Agents (or just about anyone looking to cast something), don't have all day to watch your five minute masterpiece - it's a fact, sorry! They want quick, clear and focused reel which shows off the best you. Anything more than that is pointless and will likely work against you. Whenever I look at someone's showreel, the first thing I want to see is: 'you acting', and within the first ten seconds or so. As obvious as it sounds, a lot of showreels start off with unnecessary fluff and scene padding which adds nothing to your casting potential, which will probably frustrate the person watching and put them off (it does me). I am forever skipping through showreels trying to find bits that may be useful and inform my decision to say yes, no or maybe. If your first scene is over a minute long, especially if it doesn't change or go anywhere, I would consider this a big no-no. You're only going to annoy the person watching, which is obviously the last thing you want to do. So again: get to the point! If in doubt, it's easy to find a bunch of showreels online. Watch them and take note.
Know your casting type
Before I write for actors the first thing I want to know is, "what's your casting type?". This is understandably a difficult one to recognise and decide upon, especially for newbie actors, because you're being asked to judge yourself - which is difficult to do at the best of times, let alone when your career depends on it. But 'casting type' should be seen as a beneficial term than can be used to describe the sort of character that you're most naturally going to fit, and therefore, will likely get cast as. Know your natural-self and play to your strengths because this is what is going to get you cast because often filmmakers (unlike theatre-makers) don't have a lot of time to mould your performance - they want what you've got, so give it to them. They are looking for someone who can play the role they're casting without much effort or tonnes of direction. I write scenes with a 'casting type' in mind, so you should know this (at least a little bit) before producing your own footage.
Show a variety of performances and characters
One of the main things I like to do when producing footage is to give you options with the style, genre, and vibe. This is so important, especially for someone watching your reel, because they want to see that you can do more than just the one type of character. If I see a bunch of varied characters done well, I'll know the actor can likely take direction (they'll have range). When shooting two or more scenes I also try to write and shoot the scenes in a different style - helping the viewer to imagine the actor in different scenarios. This is because more and more people are getting their showreels produced by companies, so all their footage ends up looking the same - and it can be quite off putting because you still don't stand out from the crowd. Showreels typically include clips from a host of different productions, which helps to give the impression that you've been a busy-bee, but if you're building your 'showreel from scratch', it's my job to help you achieve this look. I will often suggest after nailing your casting type in the first scene, we go for something 'against-type' in the second - it's also important to show you have range.
Minimise your scene partners
This is another difficult one to get right and something a bit of clever editing can normally fix. You don't want to cut the scene partner out completely, because the scene still needs to make narrative sense, but the focus should certainly be on you - it's your showreel we'll be watching after all. There's nothing worse than watching a showreel and feeling like the focus is on the other person. It's confusing! Whose showreel are we watching? I once had to confirm with an applicant who they were, and the last thing you want to do is confuse the person watching. At the same time, you don't want it to be all 'me, me, me', so choose scenes where you're the lead and driving force behind the narrative. The scene partners should be visually different too, to help the watcher quickly gauge who they should be focusing on (the headshot attached in the bookends will clue them up as well). But overall, you should feel like the main character in your own showreel.
Don't include self tapes and background artist footage
It's tempting to show everyone that you were in the last Bond film, well done you! But if you're just walking around in the background, it's probably not going to offer anything to the person looking to cast you and probably just confuse them. A showreel is for a different purpose - it's not a credit CV after all. If you don't have any suitable footage, get some! Nowadays, there's really no excuse to not have professional footage, focused on you, in your showreel. Also, crappy, amateur footage, that is poorly recorded, will likely do you more harm than good as well! If you've got self tapes, keep them as self tapes. Don't put them in your showreel.
Lastly, be prepared to have links on hand
Whenever I am casting something, if I am interested in the person after watching their showreel, I will often ask to see the full clips or films that feature in the reel. Whilst the showreel is the 'best of', I also want to see what else you've got - I want to see how you built and maintain a character across a short film, feature or episode. The showreel should be used as a teaser to entice the viewer into wanting to see more. If the person casting asks to see the clips, then you know you've done your job!
Thank you for reading 'What Makes A Great Showreel?'
I've been making films for over ten years now, so my thoughts and opinions have formed from that practical experience. Therefore my biggest piece of advice is to go out there and try it for yourself - it's the best way to learn. If you agree or disagree with any of my points, I'd love to hear from you. Tweet @DHshowreels with your suggestions!