Find out the dimensions of presentation space before you design your poster. Also check whether the space is vertical or horizontal (international conferences vs. national conferences).
It isn't uncommon to have a 4x8 foot horizontal display area, but this does not mean you need to fill the entire space! In fact, we discourage it. Not only will it be difficult to hang by yourself, but you will most likely be blocking an area of the poster while presenting.
Keep your poster simple and don't overload with text. Brevity is key! Summarize your information and remember the goal is to make your poster easy to scan over quickly, so use bulleted lists whenever possible. While you may not be a graphic designer, think about how you could present the information in a more visually interesting way. Use charts and graphs wherever possible instead of harder to read tables or paragraphs of text. Creative infographics have become increasingly popular and are a great way to convey information more attractively.