When I first started, AdWords was brand new and there was no such thing as quality scores. It was easier because we had fewer competitors, and traffic was relatively cheap. Nowadays there are many competitors’ and it takes a level of competency that is within the range of your competitor’s knowledge and experience, and a superior marketing strategy.
I recommend that you spend a good deal of time learning the basics before you start spending a lot of money. Start with a small budget with the expectation that you are just learning how to manage your campaigns and not relying on it for making an income. Once you learn how to get your campaigns to break-even you can begin to ramp up your spending.
Learn how to use analytics and experiment using scientific principles so that your investment in advertising isn’t wasted while you are learning how to compete in your niche and chosen marketing channel. Each campaign has the potential to provide valuable insights if you setup your campaigns properly.
As with all marketing, everything is a test. Split tests where applicable and setup serial tests where split tests are not practical. Make everything an experiment with a specific objective to gain insight. Once you string together enough marketing insights you should be able to reach profitability if you have a decent offer.