Solidify modifier

First I want to say that I’m a casual blender user. Whenever I have free time and feel like doing something creative I work on blender. With that being said I’m facing a lot of issues with solidify modifier.
A few days ago I modeled an iron man mask. I wanted to 3d print it but apparently, a bit of thickness is required in the mesh. I tried the solidify modifier but the result was a disaster. I tried tweaking the mesh a bit hoping to fix it but it didn’t work.
So, I wanted to know the factors that determine the perfection of solidify modifier and the things to avoid while working with solidify.
P.S. I tried UV unwrapping for adding textures for the final render but it didn’t go so well. So, the topology may also be an issue here.

It’s hard to tell without any pictures of your mask. Things to watch out for in general with the Solidify modifier (and other things in general) would be: Check that the object scale is applied with Ctrl+A before adding it and check that you don’t have any unwanted geometry (double vertices, stray edges, overlapping faces and the like). With Solidify you also have to be aware of situations where Blender adding your desired thickness might introduce overlaps.

solidify work fine with simple convex objects
if you have high res model might not work fast and give good results

show us some pic and what is your verts count ?

happy bl

I think overlapping thickness is my major issue here. Is there any way to avoid/fix it?

If your final plan is to 3d print something then at some point before that you are going to have to apply any modifiers. To make the geometry real in other words. Duplicate an object with the Solidify modifier first and Apply the modifier to the copy and take a look at it afterwards in Edit mode. You might then be able to solve any overlap issues by merging, sliding, moving or removing unwanted or problem vertices.

A lower initial thickness might mitigate some of these issues, but it’s hard to tell without pictures of your problem.