Dave Lister's Plan was his main vision while on Red Dwarf before the accident that wiped out the crew. It involved his buying a farm in Fiji on Earth, where land is cheap because, due to a flood, most of it was below sea level. He wanted to have a sheep and a cow and breed horses (with other horses, not with the sheep and the cow!), and keep with him his cat Frankenstein and her kittens. He hoped to get a drainage permit to get around the flooding. Lister also hoped to win the heart of Kristine Kochanski and have her come with him from Red Dwarf to the farm, where she would wear a white dress and ride the horses while Lister took care of everything else.
In the end Lister never had the guts to tell her about it, or even that he loved her. In the later storyline revisions which said that they had dated and Kochanski dumped him it is still never stated whether or not Lister told her about his plan. Lister was trying to achieve these goals in various ways, mostly by saving up all his pay and not wasting it on deodorants or other sanitation products.
His original plan was scuppered when everybody aboard except himself was killed in the radiation leak.
Lister's plan was revised after emerging from stasis three million years after the accident. His overriding goal was then to get back to Earth and find out what had happened to the human race, bringing with him the descendant of his cat, now the species Felis sapiens (to whom Lister's original plan grew to be a focal point in their religion). Lister's plan however has changed as far back ago as Future Echoes when Lister saw visions of his adult son aboard Red Dwarf, and himself still aboard as a 171-year-old, so they know they aren't leaving. Given that time travel has created a multitude of problems for the Dwarfers in the past, they have seemingly broadly abandoned it.
The plan for the Boys from the Dwarf was merely to find Red Dwarf in Series VI-Series VII, when they were stranded aboard Starbug. After the nanobots resurrect the original ships crew, the primary plan of the Dwarfers thoughout Series VIII was to escape The Tank. Once again with free run of the ship, Lister's primary goal in Back to Earth and more lately Series X is relocating lost crewmwmber and love of his life, the alive-version of Kristine Kochanski.
In the novel Better Than Life Lister does achieve getting bak to Earth, though in rather bizarre circumstances and it is now "garbage world". The recent Back to Earth specials feature him returning to Earth, though in the year 2009, only to find that he is himself not real, and then that everything was just a hallucination and that he never left Red Dwarf.
The Cat was also known for coming up with quite inventive plans in various dire situations, particularly in Series V (such as wanting to imitate Robbie Rocketpants to escape a situation), which unfortunately Kryten had to point out usually had two minor drawbacks. In one case, there was technically only one flaw, but it was such a big one as to deserve mentioning twice.