A higher ISO speed will increase the depth of field; however it will also increase the noise in the image. I use an ISO setting of 400 which seems acceptable.
Good natural lighting will also increase the depth of field as you will be able to use a lower shutter speed so enabling the use of a higher aperture setting, for instance F8 to F12. The higher the "F" number the greater and wider the depth of field will be. Some compromise may have to made, if you use too higher F number the background may also be in focus which detracts from your main subject matter.
I prefer hand held photography, therefore fixing a shutter speed of 1/250th of a second, you tend to get a fairly high aperture setting, particularly in good light. This gives you maximum depth of field, maybe one to two centimetres at the very best.
Alternatively you can set the aperture at F10 to give a wide depth of field; however in low light conditions the shutter speed will be so low that hand held photography will no longer be possible and you may have to resort to some kind of camera support.