Also, how much time do you want to spend doing real estate vs. your main job or extra work in order to fund it.

Spend more than half of your total working hours in an RE business in which you materially participate.2.

Is spending thousands on a sprinkler system worth it or do I have other options? 

If you are going to focus on listings only list ones that are priced well to sell before spending your money.

Like @Jesse Rivera mentioned above, I also go to a few sessions but spend most of my time in the lobby or at the bar making connections."

Whoever buys your flip will also spend lots of time in this room, so it’s important to make it pop.

So spending 200k on an ADU will likely not increase your property value by 200k. 

Tried QuickBooks and didn't like the Customer/Vendor aspect for properties and tenants.

Don't spend your time with other agents as a focus. 

IMO, the best strategy for that type of individual is to purchase residential property in an area they are or can become familiar with; in an area where the neighborhood is “on the rise”, typically where demand exceeds supply and people are spending $$$ on fixing up properties.