Clamping gets a lot trickier when angles are involved. If you have two pieces coming together at a non-90 degree angle, it can be difficult to get clamping pressure where you need it and if you don’t take precautions you’ll inevitably end up with gaps in the joint. There are a number of ways to tackle this problem including notching the pieces while they’re still oversized and cutting them to final shape after the glueup. You can also cut angled blocks and then glue them to your workpieces temporarily, removing them after the glueup. But one of the most reliable ways I’ve found is to use a set of clamping aids. A simple strip with an angled block at one end will allow you to get clamping pressure right where you need it, at any angle, and without damaging your work.