Easy always depends on your skill level. If you're a complete beginner, this will be a hard project to figure out. As for tutorials, I haven't seen any for this type of game. Perhaps when you figure it out, you should make one =)
As a few tips, when drawing your 'doll', you should probably have a single object draw the basic nude doll sprite (or non-nude if it's starts off with basic clothing) as well as drawing all the clothing. When you are drawing the clothing, as opposed to drawing the clothing sprites like this:
Code:
// Don't do this
draw_sprite(spr_plain_shirt,0,x,y-20);
draw_sprite(spr_fancy_pants,0,x,y);
// Etc
You would use a variable for each clothing section, so something like this:
Code:
// Do this instead
draw_sprite(global.shirt,0,x,y);
draw_sprite(global.pants,0,x,y);
// Etc
At the start of the game, you would assign those variables to default values:
Code:
global.shirt = spr_plain_shirt;
global.pants = spr_fancy_pants;
Then when you click on an item, you would reassign the variable associated with that clothing section:
Code:
// When you click on the Long Trousers clothing piece
global.pants = spr_long_trousers;
The palette swapping is not for beginners. It usually involves a shader, however, you are in luck because PixelatedPope has a palette changing tool:
https://marketplace.yoyogames.com/assets/1661/retro-palette-swapper. It costs $3.99, which it is definitely worth, but if you can't afford to put any money into the game, there's a number of palette swapping tutorials on youtube and on the forums I believe. Just have a search around and see if you can muddle your way through.