welcome & nice effort
some observations...
Looks like you've jumped straight into pixel level texturing too early which has made everything look flat like a cardboard cutout.
for example the trunk has no cylindrical feel to it.
the light source is not clear so pick one (from top left works for me).
then paint over the light and dark to build a rounded shape (dont make the transition from light and dark too gradual, looks better when more sudden).
now u have this basic form u can distort the line between light and dark to build some details like roots twisting up into the trunk, and leave surface texture to last.
u dont actually need to texture the whole surface this way as there's only some parts where the light hits and texture is more obvious.
so when u apply texture, be selective and only use a few colours from nearby instead of ur whole ramp or u will flatten the form again.
hope this makes sense