In reply to Alexander123: Greenland is a big place with a lot of options. I was in NE Greenland this year in a huge virgin area.
Its not the kind of place you go to on a "last minute deal" Southern Greenland is more accesable. The likelyhood is you need to charter a flight to get you where you want to go. Jun-Aug(summer) is more rock climbing but this means more loose exposed rock. You may be limited on where planes can land. April May(spring) is great for alpine style climbing with rock/snow and ice. Seasons do vary.
Would propably say due to cost/remoteness/logistics you are better off going with 6+ people. Commercial firms are available they cost 3 times what we paid.