The best suggestion I can make for you at this point...take at least 2 layers of fabric of the type you are planning to use for your projects. Say about 12" square. Sew some straight seams the length of your piece. In each case, mark where you have your tension setting. Only adjust your tension a bit at a time; make a test seam with a pen/marker; repeat for each setting. If you are ultimately looking to do projects with multiple layers, follow the same process with that number of layers. This will give you an idea of what settings you need for different projects. Also note the type/weight thread you have used for each as well as needle size.
There are some great discussions here regarding thread weights/needle sizes. If you do an advanced search on 'thread weight'; 'needle chart' that might give you some helpful information.