When I paint wood on a ship model, I still want it to look like wood, so I use water based paints and thin them so they don’t fill in the wood grain. It takes about 3 coats. You can lightly sand after the first coat as the water in the paint will raise the grain some. By the second coat you should not need to sand anymore. On dense woods, you can usually get away without any sanding between layers of paint.
If you want a smooth surface without wood grain showing, then you want to add a sealer or clear coat first. Then lightly sand and the paint will go on very smooth! Make sure to brush the paint on thinned, and do multiple coats. Thick coats end up with brush marks every time!
Hope that helps!