Washington did not start out very well as either a tactician or a strategist. He learned quickly, however, and ended up pretty good at both.

Washington came closest to blowing the whole American Revolution when he decided to defend New York from Brooklyn. He was totally vulnerable to having the whole Continental Army either destroyed, or cut off on Long Island, or later on Manhattan, and destroyed at the leisure of the British.

Washington saw the danger after the first day of battle in Brooklyn, and luckily, the Marblehead Regiment was able to ferry the whole Army across the East River to Manhattan that night.

If the British had moved faster with their fleet or army to cut him off, they might have won the whole war.

Even when the Army got to Manhattan, they had to race the British north to the bridges to the mainland to escape. A race which they won.

That was the closest the British came to winning the Revolution.

Washington was a quick learner. After that he made sure to never risk his army where they could not retreat to safety into the interior of the Continent.

His tactics also got better, as shown by the crossing of the Delaware and winning the battles of Trenton and Princeton.

Still, Washingtons strategy was generally better than his tactics. He knew that if he could keep the Continental Army intact, the British would have a difficult time winning the war.

When he saw his chance to catch Cornwallis in Yorktown, unsupported by the British fleet, his response was rapid, and he marched the Army (and persuaded his French allies to march) the long way down to Yorktown to the siege which proved the decisive battle of the war.

So, one of Washington's strengths was that though he was inexperienced in general command, he learned quickly. He was thoughtful about his mistakes. He never made the same mistake twice.