The Dumarest series lasted about 30 books, and I would recommend most of the early ones (particularly the Ace-Doubles) as good reading. If you're not familiar with the premise, Earl Dumarest was born on Earth, but wandered so far from it in a crowded galaxy that people in the region he is currently in think that Earth is but a legend, like "El Dorado." (The Traveller gaming system, with High and Low Passage, quicktime and basic, is loosely based on the very populated galaxy Dumarest travels in.) He picks up friends and enemies, and occaisionally a clue pointing towards Earth.

Jondelle (1973) - 10th in the series. Ourelle was the closest planet to legendary Earth that Dumarest had reached. Somehow the boy named Jondelle held the key to further data on Terra, but before Dumarest could obtain it, the child was kidnapped. Pursuit of the kidnappers led directly to a city of paranoiac killers in a country of madmen whose tempers and erratic violences terrified the rest of that world. But it was there that Dumarest could pick up the trail that led to Jondelle - and to long-lost Earth.