Apropos of this post on Covercritics: https://covercritics.com/
There's a lot of stuff that's working about the cover, but there's also some points that mean it definitely isn't the most successful version of the cover it could be.
The two points that immediately stand out as not working as they should are copy and the colours.
To start with the copy, there's a bit of word-clutter which could be condensed to both take up less space and also make things clearer and punchier.
Coming to the colours, the colour use doesn't feel balanced or like it's helping communicate the information clearly.
In particular, the red is not really working right now. Any red banner or flash in red with white writing immediate connotes either 'value' messaging or public safety information messaging. The rather bald phrasing/treatment of 'Express Investigations Series' doesn't help dispel those associations either. Red is also such a strong colour it's rather swamping the other elements
These colour issues are actually a symptom of a different issue. I think the colours have been used in an attempt to make elements stand out.
So if it's really a clarity issue, this is something that's immediately going to be helped by that aforementioned reduction in the copy. E.g. I think the information on the existing two red banners can be boiled down to a single line and thus we can immediately lose one of the red banner elements altogether.
But the other issue at play is a principle in design called 'visual hierarchy'. This is how a page or poster or cover is designed so the the eye is drawn to elements in a certain intentional and clear order. It's a really common flaw for a cover by a novice designer to fall into to not have a nice clear visual hierarchy. There's often an attempt to make everything stand out.
As for what dictates visual hierarchy, there are any number of reasons the eye picks out one area ahead of another. An obvious one is the size of the element, then there's its brightness, the boldness of colour, the heaviness of lines, how much it contrasts against its background, the space an element is given to sit in and so on.
With the existing cover there's no clear hierarchy, no clear place the eye is attracted first before flowing naturally to the next most attention-grabbing element. So it's not just about colour. There needs to be some adjustment also of sizing and spacing to get things feeling a bit more ordered.
So for instance, here's a rough adjustment of the cover that I've got to by looking at all of those factors
Firstly I've reduced the amount of text across the cover to just that I think is pertinent and enticing information for the front cover. I've boiled down the info previously set across two red banner elements to a single sentence that fits onto the one.
I have also removed the 'series number' deco previously attached to the individual book titles. I don't think it's information needed on the cover, and it only seems to necessitate more supporting wordage on the front. It's important to clear the weeds away from the novel titles and give them more space to sit in. In this case aking the titles more dominant is less about increasing their size, which I've only done a little, and more about giving them lots of negative space to sit clearly within as well as a high contrast colour treatment (near-white on near-black).
Re. that 'belly band' across the middle, copy changes and design changes go hand in hand. The key change here is that on the previous cover, as I mentioned, the same font was used for the series title as was used for the individual book titles. I have instead used a secondary font for the series title. It's only a rough choice but it shows the kind of thing I think is important in a font choice here - that while it should of course have a 'period' feel consistent with the other font, it's quite a graphic contrast, with wide rounded sans-serif letters instead of the titles' narrow serif font. I;ve also made it a different and less attention-grabbing colour/tonal value than the novel titles. Now those are the thing the eye takes in first, and the series title second, which is, I think, the right order.
Talking of colour, the most obvious change I've made in overall palette is that I've massively reduced the use of red. Red is such a strong colour it doesn't need a lot to be very effective, and too much can overwhelm all other choices.
I've also worked on balancing the top and bottom part of the cover tonally, making them more similiar. I've darkened the illustration/background of the Road to the Mansfield part considerably to be much more like the solid black of the Murder at the Mansfield area.
I've also made another small but key tweak: I've amped up the red pimento detail of the olives int he cocktail glass to tie to the red of the car illustration in the other half. Bringing out red details like that is a classic murder mystery trick, and in exchange, I've made the luggage on top of the car yellow-green to tie back the other way.
A great way of checking your design work for clarity is to completely desaturate it and look at it in monochrome. This is how the existing cover and my adjusted cover appear under that treatment:
Hopefully this makes it all the clearer what I'm talking about when I talk about visual hierarchy, balance etc.
In the existing version of the cover, the upper section of almost disappears into ea single tonal value when seen like this, because while it uses a variety of colours the tonal values are actually very similar across them all. Meanwhile the bottom section of the cover is crisp and clear in monotone, and the belly band area is at the other end of the scale from the top section - the contrast in tonal values so high it's a little uncomfortable to look at.
In my adjusted version, the book titles and their areas match each other completely for clarity and are the elements to which the eye is first drawn. The belly band area is second to come to the attention, with its lesser contrast and slightly smaller lettering.
This is, by my reckoning, exactly the order you want browsers to take things in. The titles are the most evocative part, immediately communicating genre and tone with their look and phrasing.
The fact that you immediately understand these as two titles of equal weight means the browser understands straightaway that this is bind-up of two novels. The information that the belly band area provides is therefore useful confirmation, but actually it's all pretty much said in that first glance.
That about sums up the changes I've made, but I'm also going to present an alternate layout too:
I think this clarifies things further by grouping the titles in the same space. On the whole I think the fewer distinct areas that a cover is grouped into the clearer and therefore better.
The important thing is not to get too locked-in on a layout. Often a cover having to use a lot of words to explain itself is a cover whose layout isn't working as hard as it could. Graphic design can do jobs like tell you 'this is a series title' (for example in this last layout the act that 'Express Investigations' is at the top makes it clear it's the series title.