One easy solution to the four-jump-limit is simple refueling colonies. Find a world with Sorium deposits, dump some auto-mines there, then haul on over some infrastructure and fuel refineries. It works well as a stepping stone- eventually you'll probably put some PDCs and maintenance facilities there as well, and some construction factories, and it's well on the way to becoming a colony. I try to put these, where possible, in "junction" or "nexus" systems- ones with multiple jump points. You'll want to control these systems, anyway, as it helps control the flow of NPRs through systems.
You need to build jump gates between colonies, of course, for civilian traffic.
Two other ways to jump-start colonies:
1. Invade someone's home-world. Be aware that this can take a lot of resources and troops.
2. Ruins. Once I got extremely lucky and found a Tech 5 level ruin with over 100 abandoned installations. I dumped five engineering brigades there as quickly as possible, and it quickly became my secondary research world.