Image resolution for print publishing requires a minimum of 300 - 400 ppi and higher. If the original image is not blurry or in poor condition, this will safely provide you with a good quality print image for publishing. Never increase the pixel dimensions of an image and always resize proportionately.
JPEG files are easier to work with as they are compressed files. But, TIFF files will preserve the quality of images. Publishers usually request a TIFF format for images.