@MrE I worked with a lot of tech startups to raise angel and VC money. Unless you're extraordinarily well connected or lucky, you're going to find raising private money takes at least as much dedicated time as growing sales. A couple of basic points on this endless topic.
1. You shouldn't be selling any portion of the business. It leads to potential problems with taxes, liability, ownership and bunch of other legal issues. The simplest approach is always debt financing. The investor puts in money in return for a note specifying the financing terms. No different than getting a line of credit or using a credit card which are typical alternatives.
Only naive, generous or excessively optimistic people put money into startups. That's why friends and family financing is often called "dumb money." The obvious problem for any investor owning a minority share of the company is getting their money out. It requires an acquisition, IPO or company buyback of the shares or ownership stake. Since that's entirely at the whims of the majority shareholder aka YOU, you can imagine it's not a great position for the investor. It goes without saying that you don't want a minority investor who feels they now control the business.
Of course angel investors and VCs take minority stakes, but they use legal tools to protect their investments. Complicated stuff. Convertible debt, preferred shares, piggy back rights, non-dilution clauses, etc. They also understand the necessity of making 10 - 20+ investments over a long period to properly diversify risk. Shark Tank investments do not work like everyone watching Shark Tank thinks they work. There's considerable due diligence, many investment offers are rescinded and legal protections for the investor are always in place.
2. My favorite approach to outside capital for almost every small business is royalty financing. It's sometimes called revenue financing nowadays. It's basically a loan with flexible payment terms. The payments are based on a percentage of gross (not net) monthly sales. Payments can stop when a specified total payout is reached, go on for a specified timeframe or in perpetuity. It keeps the investor motivated to help with the business (if that's the intent), they can potentially make a killer return when the company does well and it doesn't burden the business with excessive negative cashflow when times are tough.