I'm now in year 10 of being a solopreneur. My main business is https://www.pubexchange.com, an platform that helps publishers exchange traffic with other sites, as well as buy/sell traffic. My answers below are related to that, but I've also launched https://forourschool.org, a free fundraising platform for schools, as well as a few other small sites.

1. It is just me - is that a red flag?

It has never been an issue for me, but I also had that concern in the beginning. I try to be VERY responsive to emails and quickly address any issues that come up, so that usually helps address their concerns if they have any. I sometimes refer to the business as "we" (e.g. "we are rolling out new functionality"), so it may not be obvious at first that it is a one-person company, but I never deny it, and most publishers I work with and have spoken with know that it is just me.

I've worked with major publishers like Huffington Post, Aol, CNN, Time/Meredith, Yahoo, etc. Some have required approval by their information security team, which can take a very long time. There are always small issues that crop up, but being a one-person team has never stopped me from getting approved.

2. How do I set appropriate milestones for me to reach? Do I think about reaching 100 customers before reaching 5 recurring customers for example?

I never really had defined milestones. I was happy to leave that behind when I left my corporate jobs. In the early years, I had so much excitement for the business and its potential that any time another publisher said that they were interested in using the platform, it gave me more motivation to spend time on it and grow it. I guess if no one said they were interested in using it, I would have questioned continuing, but it never came up.

For reference, it took about 3 months for the first publisher to dip their toe in the platform and 6 months for a full integration (god bless them for trying it!). If you are interested, the first sites to sign up were Upworthy, Refinery29, POPSUGAR, Fashionista, and Remodelista (3 of them still use it!).

3. I'm in a small town in PNW. Does that matter if this will be an online thing anyway? Why or when do people move to big cities like Seattle/SF/NYC/Austin etc.

I'm in NYC, but I avoid in-person meetings as much as I can. They take too much time and don't provide much incremental value. I also have not had an in-person meeting since the pandemic started. So no, I don't think it matters.

4. What are some ways to do marketing? Should I even think about that before I have a few customers who are using my product consistently?

I have never spent any money on marketing. I send cold emails pretty often (which is mostly ineffective), but other than that, my business grows through word-of-mouth (it works like a social network, so there is a benefit to publishers to tell their friends, so that they can easily work with them). I also partner with some networks that work with many sites (such as ad yield management companies) who then sends their clients to me.

5. I've been inspired by the Startup School videos. Honestly though I'm not sure about fundraising and all these things, it seems very intimidating to me. What's the difference between those things and starting a company and slowly building it up?

I've never fundraised so can't help here. Unless you absolutely can not survive without outside fundraising, it would be stupid to even consider it as a 1-person company. Way too much of a distraction. That being said, if your plan to quickly build out your team, then sure, go for it.