By nature, we are not last-minute people, so we tend to plan our vacation quite far out. We usually start thinking about our summer getaway on Christmas vacation

but as odd as it seems, it usually means we end up travelling much cheaper than if we threw together a trip within 30 days or less.
In particular, by booking our accomodations quite far out, we tend to get really, really good room rates as occupancy levels are generally quite low when our reservations are made.
From there, we try to map out our "bare minimum" (hotel, flight, attraction must-do's and food) and make a plan to have it all paid off before we leave. My husband's job allows for overtime on a pretty regular basis, so once we decide to take the plunge, he will pick up extra shifts here and there which we allocate almost entirely to paying down our getaway. Both DH and I also have a second job (in addition to our "regular" jobs) from which we try to allocate all revenue to family fun endeavours. These second jobs only take up a small amount of time each month (probably only 10 hours max for me and maybe 15 for DH .... both able to be done from our home office) but add hundreds to the budget. Once the initial expenditures are fully paid, then we add on any extras from our family "wish list" as the budget allows. By starting early, we almost ALWAYS add on some really amazing extra stuff before our travel date arrives, making a great trip even better

.
We have $25 per pay deposited to a separate savings account which we use for spending cash, gas, and other incidentals on the trip (plus our park and fly hotel charges) and if it really mounts up, we can use it to purchase extra
attraction tickets not budgeted for in the original plans.
We watch Groupon, Living Social, and other sites likes hawks to secure great deals on things to do or places to eat. We've picked up deeply discounted tickets to mini golf, bowling, dinner shows, etc. which enhance our plans quite nicely. We use reputable discount ticket sites like
Undercover Tourist to save a few dollars here and there, and sign up for each attractions mailing list (and even "like" them on Facebook) to be sure we are notified of ticket deals.
We faithfully watch car rental prices and rebook reservations when rates fall.
We try to purchase all our attraction tickets in advance of the trip, as generally prices are always higher at the gate/door than they are when pre-purchased in advance.
We always inquire about discounts available through CAA membership, etc. and have found some great savings this way from time to time.
We scour the web for coupons (the International Drive website has some great ones) and use the many discounts available in the display at the hotel. Buy-one-get-one-free coupons for places like Cici's Pizza are readily available, for example, as are percent or dollar off offers for mini golf and many attractions.
We usually add something to the upcoming vacation in lieu of special occasion gifts (for example, we recently celebrated our anniversary, and instead of buying each other something, we purchased dinner show tickets to a venue we had been wanting to visit which will be used on our trip).
When all is said and done, it results in a fully-paid for vacation in advance of our departure date with ample cash in hand for souvenirs, shopping, and some impromptu extra fun along the way and meaning we have the flexibility to spoil ourselves a little while we are away. We pay cash for all meals (which we always budget for on the high side, meaning we can eat like kings and usually come home with money we didn't spend). And any excess that is left over from the current getaway gets carried over to the next vacation. We brought enough money home from our January vacation to fully purchase our airline tickets for our August trip.
The family joke is that I rarely pay full price for anything, and with enough leg work, it can easily carry over to vacation planning!