That said, I think AdWords can work really well for those who are willing to put in a little work to make sure they've understood how AdWords functions, and who understand the value of advertising in a very focused way.
One of the nice things about AdWords is that you set the limits. So, you might want to consider what it is worth to you, as an experiment, to try AdWords out. Then make sure your daily budget, campaign end-dates, etc are set so that you will spend no more.
I'd advise learning as much as you can before starting (and you are in a good place for that right here, but don't forget the info on the AdWords site), and then, once you're ready, start small. Maybe even start with just one highly targeted Ad Groups (focusing on a particular product), and a small list of carefully selected keywords (also focusing on that same product.)
I'd avoid the common trap of thinking that 10,000 random keywords are better that 10 highly targeted ones. Do use negative keywords. Write really excellent and informative Ads that will make users trust you, and also tell them you have what they just looked for. Send the user to the right page on your site.
Anyway, take your best shot, then evaluate. If you made money, then continue and refine your advertising. If you didn't make money, then either chalk it up to an experiment that didn't work, or keep at it.
The honest truth is that AdWords done well requires real work - and it is a rare advertiser that gets everything right the very first time. If you read this forum a lot, you'll see tons of stories from folks who lost money at first, and are doing really well now, having learned the ropes. ;)
Best of success if you decide to give it a try!
AWA
I suggest just starting a campaign, research some keywords, determine your budget and give it a go. I find that I rarely reach my daily budget.
I usually set up a couple campaigns with their own budgets. I can't be home monitoring costs all day, so I set it to something that I could stand to lose, but also high enough to give it a chance. Paying $10 for 100 clicks may show no profit. But what if that 101st click is a conversion? Set an affordable budget that will also give it some time to do its thing.
While I don't know what market you are aiming for, I can usually get a good idea about a keyword within a day or two. Sometimes that same day.
If you decide to give it a go, here is tool that I find helpful when searching for keywords.
[inventory.overture.com...]
Type in a keyword(s) and it will give you monthly total searches for that keyword and many variations or related ones. Those numbers are via Overture, but I don't see why Google's numbers wouldn't compare if not be higher. Does Google have anything like this?