I recommend using white, cream, brown, black, and sometimes gray for card bases. When it comes to matching colors, papers, embellishments, and etc. I usually try to pick a DP first and match the rest with it. When not using a DP (which I rarely do) try to match colors for Seasons, Holidays, or colors (that go together) from the color wheel. I hope some of this helps!
BTW: Using a DP is usually the best way to go!