Don’t Search For Your Own Keywords Over & Over
Your pay per click effectiveness in Google AdWords is measured by click through rate. If you search for a niche keyword (which should not gather a lot of impressions) a lot of times, you will deflate it’s click through rate unless you click on it.
If you click on your own ad, you will still be charged.
Before you start thinking that you can click on your ad a lot of times to make it successful, remember that Google AdWords has excellent technology to block multiple clicks.
Therefore, if you search for you ad 100 times, and only count one click, your ad will already have a CTR of only 1%. This is not always the case. If this system were straightforward, then you could pause your own ads, do lots of searches until your competitors ads are disabled, and then resume your ads. Google has many redundant systems in place to understand this type of behavior, and the ways that penalties are applied are not published.
What Google can do if they see a lot of abuse from one person is either remove your account completely, or block your IP address from accessing Google. It is always possible Google could file a lawsuit, but it is unlikely unless there are extenuating circumstances.
Broad keywords should get enough impressions that searching for it a few times will not lower your ads CTR rate by a significant amount.
Direct keywords are highly targeted relevant keywords. Searching for it a few times should not lower its CTR a lot, but many repeated searchers could harm your ads performance.