Advertising is like accounting: you're better off if you know a little bit about it yourself, and know and trust whomever you're paying to handle it for you. That way, if someone's claiming that they will submit you to 300 search engines but 275 of them are tiny search engines, region-specific search engines where your target market doesn't even go, or link farms, you will know what to ask ahead of time and find out if they're going to give you quality for the money you pay, or if they're going to meet the letter of their offerings but the results will be a bit...dodgy (for lack of a better term.)
You'll also be better equipped to tell them what you want, if you know a little bit about internet advertising. This will make their lives easier, if they're ethical, because they can charge you money and do exactly what you want them to do and give you the quality results you'd expect for your money (or can competently advise you that what you want won't yield good results.)