Learning the entire conditionals sentence structure at once can be overwhelming, so teach it in halves. Write half of the sentence on the board. For example, "If I had studied harder" or "She will go to work," and have students complete the other half. Use different tenses to show how conditionals structure changes according to tense. Or put students into groups and show them a picture. Tell each group to create one conditional sentence pertaining to the picture, then choose a strong student to correctly combine the sentences.
Conditionals can go on forever, so let your students practice as long as they need to. Arrange students in a circle and say, "If I were rich ..." The next student must finish your sentence with correct grammatical structure. For example, "I would buy a new car." After he answers, the next student must use previous student's sentence to create the first half of a new sentence: ("If I bought a new car ..."). Continue the chain until students are reasonably comfortable with each tense. Put the structure for each tense on the board during this exercise so the weaker students can reference it.
Matching tests students' logical reasoning as well as their understanding of conditionals. Before class, write full conditionals sentences on strips of paper, then cut them in half. Give each student a strip of paper with half a conditionals sentence on it. The right half of the room should get "If" sentences, and the left half gets "I would" sentences. Tell students to find their other half. You could also use questions and answers for a conditionals matching exercise. Give half of the students a question (for example, "What would you do if your car was stolen?") and the other half an answer ("I would call the police."). Always ask students to give you a complete sentence once they've found their partner.
Oftentimes, the best way to get students to work hard is to make them compete. Split your students into teams, then call one member from each team to the board. Read aloud half a conditionals sentence. The first student to write a grammatically correct and logical other half wins a point for her team. Or, write 10 conditionals sentences, then cut them up and mix up the words, but keep each sentence separate from the others. Split students into two teams and give each team five mixed-up sentences. Give them one minute to put the sentences in the correct order.