Check with your county's historic register to find out if your house has records dating back to the 1920s. You may be able to find out the original colors of your home and restore them. Under certain circumstances, restoring your home in accordance with the period may lead to tax exemptions if you join the historic register.
Consult the historic color palettes of several major brands of paint. Sherwin-Williams, Benjamin Moore and Valspar all have historical lines, as do many smaller brands. You don't have to buy the exact colors, but these will give you an idea of the color ranges for the times.
Collect paint swatches of the colors you like and try them out by taping them to the walls in various rooms. Try different color combinations to see which you like best for walls, ceilings and trim.
Take your existing furniture and decor into account if you plan to keep it after repainting. Select colors from within the ranges you've chosen that best fit your current decor.