I am young as well, turning 23 in a few months. I keep a little less than half of my account, maybe ~40% in VTI as my emergency fund. It's pretty safe for the most part... I only see it going far down if we go into a recession. However, since I am young, I can live out the bear run into a bull run and still make gains on my emergency fund (my strategy). I make sure I make enough to cover rent and food and other bills, so this 40% is mainly if I lose my job or have my car break or something big and NEED to use it. But I try my best not to use it unless I really have to.
I wish I would've put more into $BOTZ when I first invested in it, but I have about ~25% of my portfolio in it. AI is huge and is the next step in terms of how society will change. Companies will look at any ways to cut costs, and AI is how you do it... atleast that is what I believe so I am betting on that (this is completely speculative tho so dont 100% take my word on it).
I have about ~10% in FB (haha) because I wanted to play its last earnings as my first earnings play and it worked out and I gained about 3-4% from it. I still have it... haven't really found a reason to sell it yet. It's the largest marketing tool in the US atleast... ahead of Google. So it's a long-term hold for me right now... it's a small portion so it might change/might not.
I leave the rest of my portfolio in a stock that I researched heavily and believe in. I dont see the need to put it into several stocks... as it kind of means you are betting on multiple stocks versus doing your DD and betting on one. My strategy... maybe not what others think is right, but has worked good so far to me. Do your research, find a good entry and make sure in the worst case scenario (stock goes down) you are fine with holding it for the long term (believe the company will grow/have a place in the future).
I then have some cash just incase of incredible buy dips... or to add onto an existing position. I've been looking to buy more of $BOTZ to be honest, but it's been going up so much the past few weeks that I cant seem to get in on a good down day. (maybe im being greedy). But I like to not count this cash as part of my portfolio because I really don't plan on using it as willingly as the rest of my portfolio unless it's a no-brainer move and am 100% confident in it.
Take all that I say with a grain of salt. I have a degree in finance, but that does not mean I am an expert. This is just what makes sense to me and is my strategy.