This guide on creating academic posters from the University of Hull contains useful advice and information on good poster design, and the University of Leicester poster presentation guide includes a section on showing and presenting posters.
The following videos also have further advice about poster presentations.
How to make an academic poster tutorial part 1
Scientific poster design – good and bad examples! Poster tutorial part 2
The Library has books about poster presentations (for example, Bethell, E. and Milsom, C. 2014. Posters and presentations) or you can use Library Search to find books on posters within particular subject disciplines.