Finding English materials that match your CLIL syllabus is rarely easy. There are plenty of authentic texts available (newspapers and magazines, video lectures, numerous websites, podcasts, etc) but your students need language support that the creators of those resources did not take into account.You can buy textbooks for English-speaking pupils but face the same problem (though the visuals are often very helpful).
Adapting authentic texts is an excellent way to tailor resources to your needs. At first it uses much of a precious commodity you have little of as a teacher: time. In the long run, however, you will create a stock of lessons that you know are very good at helping you achieve the aims and objectives you have for the lesson and - ultimately - the entire course. There is an additional piece of really good news: adapting materials gets easier and takes less and less time as you develop the eye required to focus on the language that your pupils will need support with.
What is that language? Well, it depends on the aims of your lesson. If you want your students to be able to write a description of a process, for example, it might be a grammatical point like the passive or an academic vocabulary focus such as the use of linking words. If you are more concerned with having them grasp the fundamentals of the subject, you may have a focus on content-specific vocabulary.
One good way to focus on content-specific vocabulary in a written text is the discourse cloze. This is especially appropriate where the text has collocations that you want the learners to produce later. For a business studies lesson on marketing, I started with this
BBC article, related to a new TV programme they were running in the UK.
My lesson was aimed at learners with a high level of linguistic ability so I did not simplify the text in this case, but merely removed some words and replaced them with numbered blanks. Under the text I offered three alternatives for each space (four would also be OK). One was the missing word, and the other two were words which did not collocate with the words around it in the text. (If you are unsure about your "wrong" collocation choices, use
this tool or google them and see if they come up together.) The target collocations were then reused later in the lesson when learners had a chance to discuss marketing strategies.