Finding the "hidden" sweepstakes in any promotion is like a treasure hunt. Many sweepstakes are so widely advertised (such as the ones from Publisher's Clearing House) that most anyone, whether they have anything to do with sweepstakes or not, will be aware of them. Others will be tucked away inside a promotion of some type, and not everybody will find these.
You may need to read through some promotional fine print to find any one of these, or you may find some just by flipping through what junk mail you get, but when you find one, there's the treasure. These sweepstakes are not advertised to the general populace, therefore the odds generally would be better than most, and the prizes are often unique to the sponsor, such as a product that they sell or make themselves.
This being the case, occassionally these sweepstakes will not be run as professionally as some of the even more prominent ones, so the rules can be somewhat vague, making it a challenge to percieve what they may be wanting. In some cases, you will want to pass, as not all will be legitimate. Though, even with a vague set of rules, if you are uncertain, there are things to watch for that a legitimate sweepstakes will offer. These can include a definite start and end date, a specific prize with its own value stated (if not in the main promotion, then in the official rules), the location where the sweepstakes will be valid ( such as "open to legal residents of the fifty United States", or something of the like.), and things of this nature.
To find hidden sweepstakes, you will need to use some different techniques than you would for widely advertised sweeps. Whereas the more widely known ones will commonly be found to be available through internet searches, your favorite magazines, sweepstakes newsletters, or your local newspaper, the hidden ones are something you must train yourself to look for in daily living.
Some places you may find these hidden treasures can be:
Check the newsletter sign-up area of your favorite websites or publications. Some sweepstakes are specifically for subscribers, and can't be entered any other way. Technically, this is another type of drawing, however, these are commonly referred to as sweepstakes anyway. You might find something about these in the fine print about any newsletter you wish to sign up for.
This applies to the flats and other percieved junk mail delivered by the post office, as well as any online advertising or promotional material you might be receiving by email, though it does not include spam (this is a whole different scenario). In glancing through the promotional material, you may find web addresses for giveaways, or ways to enter for prizes by postal mail. Should you find something, be sure to read through it thoroughly to see if you will be opening yourself up to recieving any unwanted mail/email. Some will have these things as an option, for others, it is something of a qualifier for entry.
Any specific sweepstakes newsletter will sometimes have contacts that will bring them new and unusual sweepstakes that don't get out to the general public in any other fashion other than by the newsletter itself, and by word of mouth (another great way to find a hidden treasure that you won't find elsewhere). Though it isn't always easy to tell one of these from the next one, you will find that some sweepstakes will only be listed in one newsletter, and not the rest (some of these are basically exclusive sweepstakes, though others will just be lucky finds). These can also be hidden gems that will offer a variety of unusual and interesting prizes.
Product labels can often contain a lot of information that most would never take the time to read, including the sweepstakes that many would never find... so reading labels can also be a good way of finding those hidden treasures.
Once you've got your mind open to doing these things, it really doesn't need to take much time. A quick glance through will often be enough to give you those hidden treasures you've been seeking.