As a first step you may consider summarizing the central message of your poster in one or two sentences. This synopsis should hopefully act as a road map for producing a better poster.
Headings should be used to guide your viewer to important features in your research.
The language used should be clear and concise.
Text boxes should be placed in a logical visual pattern for readers to follow. Generally speaking this would mean displaying information from top to bottom then left to right and aligning text boxes with headings and graphics.
Text boxes should have plenty of white space between them. This will allow for content to be read easier. A good rule of thumb is to limit the text to about one-third of the poster space, and use lots of visuals.
Use only two types of fonts. Font types like Arial or Verdana are used extensively in posters.
Use bullets and numbering lists to identify important points.
Use images in a manner that respects copyright provisions.
Use graphics that are self-explanatory and appealing.
References and works cited can be displayed in smaller text, but not so small as to require the viewer to focus closely to read them.
Proofread the poster for spelling, grammar, readability, etc. Ask friends and family for feedback on your poster (Reading, 2019).
Acronyms should be spelled out the first time you use them.
Create a colour scheme with 2-3 colours. A good idea would be use dark text on a light-coloured background
Check whether there is a word count for your poster. Most posters would contain no more than 800 words.
Avoid the use of all uppercase letters as text in this format can be difficult to read.
Include a text box which includes details of the authors, affiliations and any acknowledgments.
Do a rough sketch of your poster on paper before you start working in a design program. Newspapers and magazines can useful sources to follow for this.
Figures should be numbered consecutively according to the order in which they are first mentioned in the text.
As much as possible, present numerical data in the form of graphs, rather than tables (Tufts,2017)
More details on poster design
This video from Berkeley University provides some additional information on creating a successful poster.