Enhance Low-Res Photos for Printing

I need an experienced photo editor to turn 1 to 5 low resolution photos into high-resolution images with a minimum of 300 DPI. This improved quality is intended for printing purposes. The ideal candidate should have a track record of trustworthiness, have a proficient understanding of image enhancement softwares and techniques. Please provide examples of your prior work, particularly projects where you successfully improved image resolution for printing.