make a complicated background with bits and pieces that you like:
and colours in the palette that you intend to work with:
Give the back ground texture by smearing, dabbing and removing and re-adding paint. Be rough. Be gentle. Be crazy. Don't worry about anything.
Add your focal pieces. Use pretty papers, bits of old map, letters, whatever you find that looks interesting.
Keep adding paint, pastel, marker, etc. Splatter and spray paint and ink until it looks nice!