Some contests allow you to enter dozens of times daily. Others limit you to a single entry during the entire sweepstakes period. Read the rules. If you can only enter once and you are heavy into sweepstakes, you should keep a log of what contests you have entered so you don't repeat any. On the other hand, if a contest allows multiple entries and you really want the prize, flood them with tries.
Sweepstakes take place for set time periods, often about a month. Some sweepstakes aficionados swear that there is an advantage to entering either at the very beginning or very end of sweepstakes.
Most people aren't interested in winning a hotel stay without plane tickets to get there, so your chances of winning are better if fewer people participate. Some sweepers do this if the hotel is driving distance from their home. Or if they hope to win airline tickets through ANOTHER contest.
OK, this is kind of new age, but successful sweepstakes entrants say they think positive and imagine that they are going to win. If they don't, they still had the pleasure of fantasizing about a trip or car or other prize.
Sweepstakes notices often say that you "may" have won a prize. Yes, that language used to be used to get people to buy magazines and such, but it also is often used because the sponsor wants to make sure you are not disqualified for some reason. So if all else seems legit, call the sponsor to confirm your win. If somebody calls YOU to say you've won something, get their name, number, company name and address so you can call back to verify.
Winnings are taxable, so you want to make good use of them. One idea is if you win something you don't want, you can sell it or swap it.