If you are a Type A gamer then reading rules will be a big part of your gaming life, accounting for a significant portion of the hours that you spend on your hobby.
A Type A gamer, in case you're not familiar with this classification (which is likely since I just made it up), is the kind of gamer who spends hard-earned money on his game collection, often hosts his game group, is likely to be the one who suggests what the group plays, has the game set up when everyone arrives, and is the one who explains the rules and gets everyone ready to play - and usually loses. A Type B gamer is the kind who only owns 2 games, doesn't care what gets played, just turns up and lets someone tell him how it works, no-one has ever seen where he lives - and he usually wins.
Over the course of my life I have spent many happy hours reading rules - which tells you which type of gamer I am. From preparing to play Red Star White Star with a school friend many years ago, right down to yesterday and completing my first read-through of This Accursed Civil War. It's a part of our hobby which gets scant attention, yet consumes many hours, and can be anticipatory fun or headache-inducing toil.
I think my favourite rules in terms of layout and useability are the Alea big boxes like Ra or Puerto Rico. Those summary side-bars are inspired, they make it so easy to just quickly review the rules before you play it again after a break.
Many wargame rules suffer in comparison with German games. Empire of the Sun and Grand Illusion have both recently defeated me by just being so long and impenetrable.
When you read a new set of rules you are attempting to imagine how the mechanics of this game work, picturing the pieces and how they are allowed to move on the board. For a wargame you want to know how many pieces you can stack together; does facing matter? do they have zones of control? how is combat resolved? are there markers that sit on units to mark morale or losses? will it all become unmanageable? how does retreat work? what is the sequence of play?
Nothing destroys my enthusiasm for a new game faster than errors in the rules. If I notice obvious mistakes or ambiguities on my first read-through, the game is likely to hit eBay in the near future. The same goes for big errata sheets posted on the web, or an impression that the designer is struggling to fix serious balance issues, or if the rules seem to be a moving target, with a new version posted every time you look. This was what killed my interest in Barbarossa to Berlin.
The order in which the rules are presented makes a big difference. For the first read-through, it helps a lot if they are sequenced to tell an unfolding story that makes sense. If rules refer forwards all the time to rules that come later, they will be very hard to understand on a first read-through.
This Accursed Civil War and Von Manstein's Backhand Blow are two rulesets that I have read recently that made good sense to me on the first read-through. The rules to The Napoleonic Wars on the other hand, made very little sense to me even after I had played the game 5 or 6 times!
Even the physical quality of the rules makes a difference. If they are printed on nice thick creamy paper with beautiful illustrations, it makes a big difference to how I feel about a game. Likewise with layout, font, brevity, and English style. Columbia Games score highly in this area.
The next step is to punch out the counters and set the game up on the table. Run through a few turns solo, then go back and read the rules again from front to back. You'll be amazed how many little things you got wrong, and this second reading will start to cement the game in your head. Internalize it as the grognards say.
Once you have mastered a game your requirements change. Now you need rules that are organized according to the sequence of play. A good index is essential, so are well-designed and accurate play-aids. You need to be able to find the information you want quickly. (Full marks to Commands and Colors Ancients for its superb play-aids.) Repetition is a killer in this respect. If the rules you want are repeated in several different sections, with subtle differences between them, confusion and disillusion awaits. See Empire of the Sun for example.
And please leave out the chatty asides and so-called "jokes" that pad out the rules with useless text. (Richard Berg are you listening?) Likewise historical notes or justifications for design decisions should be removed from the body of the rules - to the designers notes or a separate playbook.
One final dilemma - should I fold back the pages of a new rules booklet? I want it to stay pristine and new. But by the time I'm playing the game for real the rules will be starting to get a bit dog-eared and worn, and besides, a back-folded rules booklet takes up half the space on the table. So I usually end up folding them back at some point - it's a sign of a well-loved game.