The probability is low that they are going to go looking for you. So you have to locate and select the underwriter who will best meet your needs. It's important, but not necessary, to find an underwriter who has done previous IPO's in your industry. An underwriter who has done other IPO's in your industry is more likely to be familiar with the structure of the industry, pricing the issue should be easier, selling the offering to a syndicate will be easier, and they will already have worked or are working with analysts covering the industry and will already have an open door to them. Some underwriters specialize in IPO's in a few industries.
Some underwriters specialize in debt offerings.
And other underwriters specialize in small unproven and speculative companies. It's also very important that the underwriter selected be able to put together a strong syndicate. The desirable choice is to have a broad base of institutional and individual investors. A good syndicate is highly effective in this. The company wants as many brokers in as many different branches as possible selling the stock.