That's a professional question. DOF is tricky and you need to practice. There is also some information on how far you stop down that is important. First for a normal shot the DOF lies one third in front of the subject and two thirds behind the subject. As you move in closer to a subject the DOF changes to 50% in front and 50% behind the subject. This is important if you want sharp and crisp focus in your image as the understanding of DOF allows you to open your lens. I have some very budget minded lenses which I do not recommend that anyone serious about photography should buy but I will tell you that when all is right the images can be amazing. Better glass will do a better job in most cases but my point is understanding what it takes to get a good technical shot will work with all lenses. I think others may have some points also so less start with point one
1. Always make sure the camera is rock solid. Any movement even from mirror slap can and will have a degrading effect on the image.
2. Always use a lens hood. Look at your lens and make sure it is in the shade of the lens hood. If not hold up a card and shade it. If you don't do this you could lose contrast and your image could turn muddy and dull.
3. This next one is going to get me into trouble but here it is. If you are
shooting digital never stop down any more then you need to after the first 2 or 3 f stops. With all lenses as you close down the light is diffracted by the side of the aperture as you stop down more you get more diffraction. With a view camera I used to shoot at f22 to f64 with only a slight degradation of the image but with digital after f8 or so (depends on the lens) the image degrades noticeably when compared to a wider open lens.
It's like taking a 14 mega pixel camera and getting a 4 mega pixel image.
The reason for this in digital is partly due to the less amount of light the sensor has to work with as well as the diffraction caused by stopping down.
Well that was a mouth full and I hope that I am not in to much hot water but please test and you will be amazed. If you are getting some good images and some no so good review the images and see what f stop was used you may be suprised.