For wood and fibers, we use glutaraldehyde fixation followed optionally with 4% Osmium tetroxide fixation and finally, graded ethanol dehydration followed by resin (LR white or Epon) infiltration prior to embedding.

The procedure however varies greatly depending on the sample itself.

For detailed information, I strongly suggest you get hold of Ruzin's book on plant microscopy : https://www.amazon.com/Plant-Microtechnique-Microscopy-Steven-Ruzin/dp/0195089561

It is truly a trove of information for preparing plant material for LM and SEM.