Hi Dierdre!
You first should determine what are all the "can't miss" parks, places, or activities you'd like to experience. From there, consider an initial plan: How many days at the Parks, whether to stay at a resort or not, whether to get the Dining Plan, etc....
I should note that Disney is offering Free Dining during portions of your stay. What they've done for us in the past, was even though not all days were covered under the discount, the days that were, we were able to get a discount for. To get more details on Special Offers, click here.
In terms of cost effective, getting a Disney Base Ticket and staying at a Value resort is the way to go. If you're a AAA member, they are constantly offering deals that can save you money as well.
When our family is on a tight budget, sometimes we'll bring snacks from home to off-set the premium snack costs in the Parks. Also, there's nothing wrong with purchasing a Disney souvenir or two BEFORE your trip off-site, to save a few dollars.
Universal is not part of Disney, so you'd have to consult a travel agent to see if they offer Universal/Disney combo deals...
So, there are a few angles you can approach in terms of saving money. Good luck and have fun on your trip!