Tripod is crucial in taking landscape.
Flash may not be that crucial yet for you.
Just remember that Flash and Tripod may last longer than your camera body. So choose your flash and tripod wisely.
For me, i started off with the D90 Kit set and then i browse through the lens catalogs, assessories catalogs, online store etc. . .
i list down things that i wish to expand and buy.
Just my 2 cents . . . go for a good tripod first . . .