Provided you have the time and necessary willpower you could also do focus stacking.
Meaning, you take multiple pictures from the same position with different focus points and let software (for example Helicon) calculate a single sharp picture from them.
It does get very time expensive though because the photo taking process rises by a factor of up to 10.
I did notice though that you get away with a lot less pictures because the pictures you DO have are a lot more detailed.
Definitely worth a try for objects with a narrow focus plane and pretty much the only way for very small objects.