1) Respect The Base: The first rule of politics is, "take care of your base." That doesn't mean you give your supporters everything they want, but if your base isn't happy, you're going to have a rough time. Why? Because they're the people who donate money, volunteer to help candidates, talk you up to their friends, defend you when you're under attack, and, when they're happy at least, they’ll crawl over broken glass to come out and vote for you.
Democrats bend over backwards to make their supporters happy. They pay an enormous amount of attention to what their activists have to say, are constantly doing things to try to make them happy, and even though they can't always give them what they want, they go to great lengths to please them.
But, the Republicans in DC? Most of them treat their biggest supporters with polite indifference at best and contempt at worst. On issues of great import to conservatives like fiscal conservatism, illegal immigration, and judges (See the nomination of Harriet Miers for a perfect example of this), the DC GOP have gone out of their way to kick their own biggest supporters in the teeth. Because of that, the base hasn't been happy with the Republican Party since early 2005 and quite frankly, unless some significant changes are made, there’s probably not going to be an about face any time soon.
2) Stay Out Of The Primaries: One of the most aggravating things about the 2006 election was the Republican Party’s involvement in the primaries.
The worst example of this was the National Republican Senatorial Committee's insistence on supporting Lincoln Chafee, a left of center Republican who didn't vote for George Bush in 2004, in a tough Rhode Island primary against Steven Laffey. What was the result of that brilliant maneuver? The NRSC lagged far behind their Democratic counterparts in fund raising because conservatives withheld their donations in retaliation and in the end, Chafee still lost. This isn't the only Republican Party screw-up of this sort either. Look at the Arlen Specter vs. Pat Toomey battle in 2004 and the Randy Graf vs. Steve Huffman race in 2006. In each case, the party's interference came back and bit them hard in the behind.
Unlike the Republicans, the Democrats are generally smart enough to stay out of primaries because they understand that if they get involved, they will inevitably be fighting against their own base to help someone who's probably not much of an asset in getting their agenda through. This is part of the reason that Democrats in Congress are much more disciplined than Republicans, because the Democrats can't thumb their noses at their biggest supporters and then expect the party to come running to save them when they get a primary challenge.