First, keep a log of what you've won. It helps you remember how much you have won and encourages you to keep going when you think you haven't won much lately.
For me, I've cut back my time sweeping considerably but have still won 11 times this year. Nothing big, a t-shirt, some DVDs, books, Pace salsa coupons for free jars, a CD, and my 'biggest' win of the year a Leapster 2 ($60) that we're saving for a Christmas present. Last year, I won 15 times for the whole year where biggest win was $150 tickets to a show. In 2008 when I sweeped quite a bit more, I won 176 times over the course of the year. About half of the prizes were digital downloads so it wasn't as impressive a haul as it might sound, but still pulled in some good stuff, again show tix, dvds, books, pace coupons... about 10 t-shirts, cds... 2007 had 130 wins.
I've never won a trip but did win a
nintendo sweepstakes DS video game system that I traded for a nice camera that I still use today...
Sometimes you win things you don't need, like you wanted 1st prize but got 2nd and have no use for that one... so you trade things...
It is fun waiting for the mail to see if something good comes.... as you aren't always told before things show up if you won.
To try to get a "win" under your belt quickly, checkout the list of expiring sweeps as they'll end sooner. Otherwise, if you only watch the new sweeps list, you might not win something for over a year....