Band-wise, start with Genesis. They're considered the most influential progressive rock group to progressive rock lovers. Becoming a big stadium band by the 1980s and exploring almost every style of progressive rock there is throughout their career, they are a band that is in the hearts of music lovers both inside and outside of the progressive rock world.
To start listening to this timeless band, get hold of their 3-disc compilation "The Platinum Collection" and listen to the three discs in order. The first disc features a lot of their pop music, some of which you may recognize from the radio, but it also contains some progressive rock material, mainly the two-part song "Home By The Sea" which is a highly accessible prog song to get into compared to others.
The second disc contains a good mixture of progressive rock and pop music, and this particular disc is great for acquiring a taste in the genre as it’s very accessible and light here, mainly due to the warm vocals of Phil Collins.
The third disc is the most challenging – it features just nine tracks from the Peter Gabriel era, with five of them clocking in at eight minutes and over. Start off by listening to the first two discs a few times, and then check out the third disc. It can be overwhelming due to the amount of talent on display and the lengths of the songs, especially on the third one, but don't give up. These songs are very special to many progressive rock fans, and soon you’ll learn to love them.
Take note of the fast and complex keyboard solos from virtuoso Tony Banks, Steve Hackett’s usage of melodic guitar to create atmosphere, the intricate drumming from Phil Collins, Mike Rutherford’s clever bass playing and Peter Gabriel’s dark, powerful vocals.