I have a technique for avoiding writer's block - those moments when you're tired, you've had a very trying day, and the last thing you want to do is start wrestling with disobedient characters.
Simply, stop one and a half sentences before the end of your writing session - you know what the one and a half sentences will be, you just don't write them. So you finish with an incomplete sentence - just one clause perhaps.
Then, when you start your next writing session, just resume where you left off. Write the other clause to finish the incomplete sentence, then write the next sentence (the one that was still held in your head).
Simply, stop one and a half sentences before the end of your writing session - you know what the one and a half sentences will be, you just don't write them. So you finish with an incomplete sentence - just one clause perhaps.
Then, when you start your next writing session, just resume where you left off. Write the other clause to finish the incomplete sentence, then write the next sentence (the one that was still held in your head).
By now, you are in full flow and on you charge!