Create #remarketing campaigns from the very start!
Clicks from the Display Network are often much cheaper compared to Search, and can still convert well if you take your time setting up your targeting.
It may sound obvious, but you really need to define what it is you want to achieve by using AdWords. Defining this Key Performance Indicator will help you evaluate targeting methods later on and figure out which is bringing you the greatest value.
Too often advertisers look at inconclusive metrics such as clickthrough rate and evaluate their AdWords performance based on those. But it’s far more important to measure all important actions on your website, such as phone calls and registrations. You can also build a measurement model based on your business objectives.
Start with the Search Network, and build a winning list of keywords which you want to target (you can use Keyword Planner to find ideas). But first make sure that you understand how different match types work. If you don’t have time to check your AdWords account each day, you could start with an exclusively Exact Match campaign (no negatives; no irrelevant traffic; good dreams at night). This campaign type will get much lower traffic than a campaign using broad match keywords, but it will also give you more control over your ad spend.