sentence writing

They're both a bit problematic, as a rule of thumb try to use as few words as possible, each word should add something to the sentence.

Going by that rule the second one is better assuming you meant to say paint palette and not repeat paintbrush again. You don't need to say paint palette, palette will suffice as it's pretty clear by context that's what it is.

Also you seem to be cramming a lot into one sentence. Do you really need to say that the wooden chair is next to him in that sentence?

How about, Seated at his desk, Joe dabbed his paintbrush in the palette he kept on a wooden chair beside him.

Pablo dabbled upon the palette, it was all too easel.

Many thanks! How about omit "he kept" in your version? If you insist, could you please tell me why?

It all comes down to style, using he kept says that this is something he has done before, it's practiced. Otherwise it could just be something that happened then and there without any thought or it could still mean it was something he'd done before and everything in between.. It's more vague, and really down to you what you want to convey.

I prefer keeping he kept, it tells the reader something about the character's habits and gives the sense of character development, but that's just me. It's all down to your own style and what you want to convey.

It helps a lot ! Thank you so much!