1. Search for offers for airline tickets in different sites like skyscanner.com
Low cost airlines: Southwest Airlines, Ryanair, easyJet, Air Asia, JetBlue etc.
2. Book tickets early so you can get special offers.
3. For your accommodation you have several choices:
i) Airbnb: is an online community marketplace that connects people looking to rent their homes with people who are looking for accommodations. You can book the whole house for several prices. The most of houses provide to you kitchen, shower, bedroom, TV, Wifi etc.
ii) Couchsurfing: The website provides a platform for members to stay as a guest at someone's home, host travelers, meet other members, or join an event. Is the most cheap way for your accommodation and you will meet new people.
iii) Hostels
4. You can find different places to eat tasty and cheap.
5. You can enjoy your trip without a lot of money.