I have created many banners and standing banners and also flyers, posters, and brochures for many occassions. I design those banners using photoshop and sometimes illustrator if necessary. Since the size of a banner can be very big, using 300 pixel/inch resolution on photoshop will be tedious because it can freeze your computer because of the size. So, first I make the banner in low res about 40-70 pixel/inch and make all photoshop objects into shape or txt so when i scale it up, it will still maintain the perfect sharp edges.