Having spent my morning trying to put together tonal outfits from my wardrobe, I have a very clear answer to your title question: YES tonal matching is challenging for me!

FI, I agree that tonal works best if you can achieve a subtle gradation, and that is so hard. It basically means you need a minimum of three shades that all work together in terms of undertones/temperature/etc. And then if you want it to look really good you have accessories complements like Angie's beautiful colour capsules. My closet doesn't (and will probably never) have that sort of depth in any category. If I maintained a very strict colour palette I might be able to do it.

Irina, I will take that as a compliment

I'm nodding along with Brooklyn. Creating a tonal outfit is about putting a look together with colours that are close together on the colour wheel. You can use various tones of blue, like she showed with her Finds.

For dark blue, I like to mix textures - like denim and wool - and add light blue to the mix.

Also nodding along to La Ped's wise observations. To create a tonal look with NON-neutrals, you need more items in the non-neutrals. You also need to maintain a disciplined approach when you add the colours to your wardrobe. They have to all work together in the right items - the shoes too - and you need to be thoughtful about it. It takes time, patience and resources! My wardrobe took a long time to get to this point. But now that my tools are sharp, I can create a tonal look in non-neutrals very easily. I'd like to add citron to the mix, so I need citron bottoms. Maybe some shocking pink pants too. All in good time. No rush!

Thank you very much for thoughtful responses. I learned a great deal while reading your ideas and observations.
I have color palette that consists of neutrals where all colors work well with each other. I became more interested in tonal and monochrome outfits recently, I’m looking for the ways to better utilize clothes that I have. I learned that I prefer low contrast in tonal outfits and colors from the same family. Also, I realized that I don’t like accessories in the same color. And I should probably leave navy/inc alone with an exception of denim

These outfits are stunning! Very elegant and they make me think of minimalist Italian designers.

I enjoy tonal outfits, and do them both with neutrals and colors, although much more often with neutrals. I tend to weary tonal navy outfits, too, and the trick is, like Angie says, to mix textures so it looks intentional as opposed to slightly mismatched flat pieces. I am fine with wearing lighter an darker navies together, as long as their undertones match. Below I have attached pieces for one of the outfits I have worn in the past: wool blazer, lace top, textured/chambray pants, snakeskin booties.

I tend to wear tonal neutrals - white, black and blue rather than full on colour. However, I tend to add a pop of colour with a handbag or coloured pump to make it feel like me.