One must rather believe in having a strong concept. Treatment can be varied – for example, the colours that are used across artworks can very well be inspired by the subjects and personalities of the concepts. One might want to focus more on the big idea rather than the treatments and beautifying the elements. If you have a strong idea in your hand, you will eventually find a way to make it look good. The need is to be more simple yet effective. Likewise, quirkiness need not and may not always a part of the illustrations.
There are certain subjects that may be serious, but you want to make it more fun to get the whole serious tone out – it entirely depends on what exactly you want to communicate. In the same way, do not really look to maintain symmetry and proportion in compositions, if that suits one's temperament, style and approach. For example, in some of the illustrations, there is no symmetry that is trying to be achieved – it's just the way of drawing;, not force-fitting any rules while one is drawing.
It can be very simple and minimalistic, or it can have those tiny details that add value to your subject. Adding minor details are actually the observations that you are trying to put into your design, which is also a great way to make your design truly relevant. People, their stories, and events happening around are what mostly inspire any form of artwork, directly or indirectly. All one has to do is observe; that's all it takes – a keen sense of observation. The stories that you are trying to communicate through visuals, one must recognise, the need of strong colour systems as well – colours that decide the mood of the illustration.
If artists and designers of all forms focus on the 3H's (Head, Heart and Hands), their work will positively impact and take forward the process and future results of the field – that would be true evolution. The 'Head' stands for the ideation. The 'Heart' is for being empathetic towards the people you are working for. Then, lastly, all you need is skilful 'Hands' to execute that big idea that is visually appetising. That is the core of achieving what is desired. If these three things can be ensured in the years to come, then the creative communication can not only take a big step forward but can make a giant leap instead, especially with the kind of technology that is available to us today.