Noah,
Congratulations on your first flip. I see no issue with using your own cash to buy properties, I do the same thing quite often. If I have the cash available I see no reason to go to someone else to get it. I would echo that you hire people to work on your projects that have their own businesses not hire employees. Also make sure you work with your insurance advisor to ensure you have the right coverage. I would not own one investment property without it being within a business structure like an LLC. Get with your asset protection attorney and CPA to find out what structure makes the most sense for you and your particular situation.
A long time ago someone asked me what I could hire someone for to tear out old cabinets, carpet, drywall, and other task. They continued to ask what I could hire someone for to paint, install a vanity, install lights and so on. After giving them the cost for each they told me that every time I do one of those things I am working for that amount. This got me thinking....
I, like you it sounds, have the skill set to do many of the repairs myself. This can be a good or a bad thing. If you really enjoy doing those things than so be it keep doing them. If on the other hand you do them to save money then maybe take a closer look at your options. What I determined a long time ago is that I need to focus my attention on what matters the most for my real estate investing business and that is finding and negotiating the deals. Yes I may make less on each project by hiring out the work, but I will do a lot more deals and thus likely make more money overall.
I do not hire general contractors that oversee my projects. I hire the specific contractors I need to do each thing I need done. I find, for me, I save a lot of money by doing it that way. My, and yours as well, knowledge of how things should be done, what they should cost, and how long they should take is very valuable. I have had a lot of contractors over the years try to blow smoke up my rear thinking I didn't know what needed to be done and how much it was really going to cost. This is where your experience doing the rehab yourself will pay off. Now that you have that knowledge you can use it to hire and oversee those that do the work. Anyway, just something to think about.
At the end of the day you are personally responsible for the success or failure of your business so you need to decide how you want to run it. There are many ways to be successful in real estate. You only need to find one that works for you to be profitable. Good luck.