help pls german gcseWatch
german.net is a lifesaver too, i would check out the sections on conjunctions and modal verbs. Each activity is colour coded by difficulty, but it's super helpful from gcse to degree level.
One of the things that tripped me up at gcse were conjunctions, remember there are only 5 coordinating ones (aber, und, oder, sondern, denn), so all the others will send the verb to the end. Good luck!