If you are a somewhat competent artist, designing a good poster really comes down just to the idea. There are some set rules to follow when designing a poster but most of them are the same basic set of rules that you follow when painting.
A poster is a visual presentation of information. It’s purpose is to convey the information in a direct and eye catching way, without the need of extra verbal comment.
There are many types of posters and how you approach the design depends on what type of poster you are making. You will not design a poster that promotes a gathering the same way you would design a poster for a movie. The basic concepts of design stay mostly the same but the information is different and your design has to convey just that.
Before you start to design a poster you need to make a plan. Will you just be using images, just text or most probably both at once? After that gather your information and break it down to the bare minimum. Overburdance of information may detract from what is actually important. Then arrange the information in a hierarchy of importance. The info that is more important should stand out more than everything else.
If you are working with text, choosing the right type matters. If you are designing a poster for a children’s book, “feast of flesh” isn’t really a good type choice. Changing up the type isn’t a bad idea but be moderate. Different fonts bring life to a design but using a different font for every column or header is overkill. Text also needs to be readable. That includes a readable type, placement and background.
What kind of image you use on the poster is up to you. It can be a photo, illustration, painting, drawing, whatever. Just keep in mind that everything else has to be consistent with your image.
The poster should be balanced. Composition makes or breaks the design, especially with a minimalist approach. The same basics apply as with painting, drawing, photography, etc. Composition rules stay the same.
I like a more minimalist approach to design but that’s not a rule. Artist like Drew Struzan use a more painting like approach and the results are amazing. Hippy and psychedelic designs follow the exact opposite of minimalism. They overfill the design with curves, lines and colors because the idea is to keep the viewer involved as long as possible and find new things every time he/she looks at it.
These days when digital design is more prevalent other problems arise. With free domain vector resources people started depending on them too much (especially wannabe designers :P). Using free domain vectors isn’t really wrong but the problem is that these vectors are generic and aren’t catered specifically to your design plan, so the free vectors then dictate how your design flows. You want that to work the other way around. First make a plan and then design vectors around THAT.
Another problem is that these free vectors tend to make people think they need a lot of them. I think this mentality stems from the ease of use. Just copy/pasting the vectors is fast and easy, so the “wannabes” tend to think a lot of them are necessary to excuse their lack of work and mask the fact that they didn’t make themself. I can’t tell you how many times an organization just assigned one of their employees that dabbles in design a bit instead of hiring an actual designer. The results are usually a disaster.
If you are a good designer, make your own vectors. If you don’t know how… LEARN! It’s really not hard and is well worth the time spent.
Also if your design is a series keep in mind it needs to be consistent. If you make a series of posters for the same event use the same fonts and styles as you did with every other design in the series. A good example of consistent design is a series of posters by Jesús Prudencio with famous cars from movies.
That ALSO isn’t a must rule. I did a series of posters for my thesis work and none of them look the same. The only consistent thing about them is the idea and the illustration style. Fonts and compositions varied though but that was because the concept of the series warrants different designs.
Making sketches and preparing is also a good idea. First design on paper and spend a day or two with the design. Trust me… Also the design shouldn’t appeal just to artists and designers but to everyone.
In the end, how you approach poster design, is actually pretty basic but no one gets it right the first few times. Try making a couple of fake posters using your own ideas, fake or even real companies to get a feel for it.