It depends on the problems with it. Various video (and audio) filters are designed for correction and improvement: Color Grading, Brightness, Contrast, White Balance, Hue/Lightness/Saturation, Crop, Lens Correction, Reduce Noise, Sharpen, and Stabilize. Also, you might want to remove interlacing and you can export as progressive and control the quality of that (Deinterlacer). After cleaning, you might want to use a very high quality scaler to increase resolution because maybe you will use it a (U)HD project and the other tool does scale as well. In that case, in Export you can set the Interpolation to Lanczos.
Made a small demo using some color clips to show you a few simple and some more complex transitions and effects you can use with Shotcut. Take a look at the filters to see how they are applied. Hope this will help with any future projects you might have.
Slideshow.mlt (26.1 KB)
THanks for answering! i really appreciate it!