Thanks to the power of the Internet, more and more readers are receiving recommendations about authors they should check out. However, given the prolific nature of some authors and their dabbling in multiple series (complete with multiple starting points, thanks to prequels, first-published novels and so on), finding a good starting point can be tricky.
A case in point is Peter F. Hamilton, who has written multiple novels, some set in different universes, with his individual settings and universes having multiple entry points. So where is the best place to start with his work?
The Greg Mandel Universe
In Hamilton's Greg Mandel Trilogy, mid-21st Century Britain has been ravaged by global warming, an extremist Communist government, a bloody civil war, and, most traumatic of all, the capital of the nation being moved to Peterborough (easily the single most far-fetched concept in the entirety of Hamilton's fiction). In the aftermath of these catastrophes, semi-psychic soldier of fortune Greg Mandel investigates various crimes and corporate politics. It's all rousing stuff.
Fortunately, Hamilton has only ever written three books set in this universe: Mindstar Rising (1993), A Quantum Murder (1994) and The Nanoflower (1995). So if you want to check this series out, start with Mindstar Rising. Simple.
The Night's Dawn Universe
In Hamilton's Night's Dawn setting, humanity has expanded into space and, by the early 27th Century, has colonised some 860 planets and split into two divergent strains, the technology-enhanced Adamists and the genetically-engineered Edenists, and met several alien races. This is big-canvas, epic space opera of the highest order.
There are two viable starting points for this setting. There is the Night's Dawn Trilogy, of which the first book is The Reality Dysfunction (1996), Hamilton's single finest novel. There is also a short story collection spanning 500-odd years leading up to the first novel, entitled A Second Chance at Eden (1998). The collection is shorter and features a greater variety of stories and prose styles, and may make for a more digestible taster of Hamilton's writing skills before embarking on the 3,600 pages of the trilogy.
The Commonwealth Universe
Hamilton's Commonwealth setting follows a different path to Night's Dawn. Whilst still serving as epic space opera, the series features more advanced technology based around wormholes. Wormhole portals link the worlds of the Intersolar Commonwealth together, so people literally take a train ride from one planet to another. There are few spaceships (to start off with) and the setting is slightly more exotic, with humans living for centuries thanks to rejuvenation technology.
There are three entry points to this sequence. Misspent Youth (2002) is, chronologically, the earliest volume in the sequence, set in the 2040s in Britain where the rejuvenation technology has just been invented. Whilst viable, the book is probably Hamilton's weakest single novel and features little in common with the larger events of the later books. There are a couple of Easter egg mentions in the later novels to characters and events in Misspent Youth, but overall I'd put it off until later.
Pandora's Star (2004) is the first book in the Commonwealth Saga duology, set 340 years after Misspent Youth, and makes for the best entry point to this setting. Its direct sequel is Judas Unchained (2005), which is less the second book in the series and more the other half of Pandora's Star.
The Dreaming Void (2007) picks up on events in the Commonwealth setting 1,200 years later, and is the first in the Void Trilogy, followed by The Temporal Void (2008) and The Evolutionary Void (2010). Hamilton is also planning a further trilogy set in this universe. Whilst Hamilton goes to some lengths to make The Dreaming Void stand alone, it does spoil the end of The Commonwealth Saga and reveals which characters from the earlier series survive. At least three major characters from Commonwealth also appear in the Void sequence. For these reasons, whilst it is not impossible to enjoy the Void books on their own, I would heavily recommend starting with Pandora's Star first.
These are pretty straightforward. Fallen Dragon (2001) and Great North Road (2012, planned) are self-contained novels set in their own universes with no relation to anything else Hamilton has written. For these reasons, they can be read at any point with no problem.
If you want to read a varied sample of Hamilton trying different narrative devices, playing with different prose styles and so on, start with A Second Chance at Eden.
If you want to read a completed, epic SF space opera series, start with The Reality Dysfunction.
If you want to read a near-future, SF detective thriller, start with Mindstar Rising.
If you want a totally stand-alone novel with no sequels, start with Fallen Dragon.
If you want to read a really long (five books and climbing) series, start with Pandora's Star.
Hope that helps!