PPC campaigns allow you to test a variety of strategies in a number of ways. One time-tested approach is to create as many ad groups as possible. You only have to check your campaigns once a day after they are launched. Monitoring your account, you will notice that many of the ad groups will receive impressions for the keywords that you are using. How long you wish to monitor them is up to you. You'll notice that certain ad groups are not working, so get rid of those. When you do this, you will free up more money for your daily budget. This is called pairing down. You can enhance your productive at groups, plus manage your money in a much smarter way.
When doing PPC advertising on Google, the quality score is cumulative. You need to remember that. So, for instance, all of your previous PPC campaigns will factor into the overall quality score that you get. Let's say in the past you were slapped for something that had to do with quality - this will drop your score down significantly. It is possible to find out about more of their documentation regarding terms of service on their website. Or, you can find the information elsewhere such as in an article like this. As you see, it is in your best interest to do the best you can all the time.
In the not so distant past, Google started rejecting PPC ads with the destination URL that went to a squeeze page. That was devastating to many people. They eliminated thin sites as a destination for an ad, making this a policy everyone had to abide by. People that were using Adwords could no longer build their lists with squeeze pages. Instead of sending people to a squeeze page that is relatively simple, and more elaborate one needs to be submitted instead. Your overall quality score and actually be harmed if it is rejected. Even though Google has done this, people still find a way, inevitably, to build a list with Adwords. Getting around this is easy - just send people to a landing page on your website that has an opt in box with other pages as well.
When it comes to advertising online, Pay Per Click isn't all that different from the other methods you an try. Just figure out which sources are the most trustworthy and learn the best way to do it. Then you just need to make yourself actually get started and it is okay to proceed cautiously until you feel more comfortable. In addition to gaining valuable experience, you'll get the confidence you need to keep going if you make a mistake.