So, I’ve made a few very small games so far, that have seemed to work fairly well. My only problem is that these games have taken me ~1 day to make, so I’m not particularly learning anything from them.
So, before I start to try and delve into a larger game, does anyone have any personal advice on making their first ‘slightly-larger-than-the-pitifully-small’ games?
Why not just add more features to your simple games?
Could you show what you’re doing now?
Been there, done that 
Here’s the game I just finished (the files name was messing around, and I just named it Game because why not) http://www.mediafire.com/download/9ewq0h0lhbt9x9i/Game.zip
Pretty good for a “tiny little game”. So you want slightly larger than pitifully small? Separate gameplay into waves of hazards, with different waves containing different kinds of hazards. Also add random things to appear that the player is supposed to try and collect. Introduce new mechanics every few waves and then create more elaborate challenges by combining those new mechanics in different ways. Keep increasing the complexity and challenge of the game as the levels progress and try to achieve a good difficulty curve.
This should take you a couple of weeks, enjoy!
Or did you have something else in mind?
I guess I’ll do that then!
Make it an MMO. MMOs are complex. 
& add zombies & crafting
There’s nothing wrong with building lots of small pieces that later can come together.
Add UI, every game needs UI so it’s always good practice
Especially since there’s a relatively new one now. And it makes use of UnityEvents