Hey Ali. Congrats on getting started. I'm also 25 and somehow managed to acquire about 170 units. Not sure your exact financial situation, but what really helped me was constantly finding the next deal and then figuring out what I would do with it after the fact. Wholesale it, flip it, keep it as a rental, owner finance it. Given, I do this business full time which I'm sure makes a difference. By having a lot of deal flow and wholesaling a lot of the deals, particularly when I first started, it allowed me to run into people that would ultimately become lenders and partners.
Scaling to a decent portfolio in a short amount of time isn't always what it's talked up to be. It demands that I keep a large sum of cash sitting in the bank doing nothing in order to protect myself (some people in this business will tell you having cash is a cardinal sin). Due to this, I'm not able to be as aggressive and flexible on picking up more houses to flip/spending money on marketing. Part of me wishes I didn't buy so many rentals so quickly so that I could better utilize my cash to spend more on marketing to generate even more active income. The point I'm trying to make is: the more you acquire, the more liability you take on. Also, cash doesn't go as far as it does when you don't have many liabilities. 100k in the bank for me means a lot less than 100k in the bank for someone who only owns 1 property. 100k for me means 3 months of mortgage payments (if everyone stopped paying) 100k for the person who owns 1 property means years worth of expenses set aside and they can aggressively spend money on marketing and trying different channels.
If you're hell bent on acquiring more long term holds in a short amount of time, Always focus on the next deal. Don't try to hold on to every deal, don't be afraid to wholesale them out to generate short term cash/build relationships. Deals are like buses, another one comes every 15 minutes. Pick 1 marketing channel and stick with it until you see success, bouncing around doesn't work. Every marketing channel works as long as you work. Find people you can work with, borrow from, and learn a lot about creative finance it's becoming the way of the future with the direction the market is headed in.