Courtwinds were my first protection spirits and the first angels I really got visuals on. Something like the "white tornado" of advertisements of old. I think that' not by accident -- they're pretty easy to perceive and you don't have to wonder if your perceptions are real.
They're a good, maybe the best, protection spirits to start with. I am big into Protection and they are at the forefront and the foundation of my protection plan.
To digress a little: A protection plan really is a must -- don't abdicate and leave it up to the sprits. My protection plan: I have a Courtwind in a crystal vessel in the NE, NW, SE, SW windows on the first floor and N,S,E,W watchers at each corresponding windows on the second floor, there are more than 4 such windows but I started that way but it felt better to have each major direction have its own watcher. Later, I added lampades to support the watchers.
I also have some dark arts spirits tasked with protection, but they guard the entrances and the perimeters. these are not in 4s, though: 3 fenrirs at the back door, a pack of hellhounds at the front door, 5 gargoyles from high vantage points and running the perimeter. There are also spirits who like being tasked with protecting other spirits.
At the center of this is Ash's Ultimate Protection Spell, which I did for three months at the winter solstice. But I have also followed the layering rule and there are several other CH bindings in support of that. Everyone is tasks with security, but some spirits have it as their primary task.
There's a Phoenix hanging in the skylight at the center of the house, but I think there could be a better choice for protection. She does like it there and shines a nice light down the stairs.
The Eight Tenets of Ritual Magick
1. Expect the unexpected;
2. Magic has no morality;
3. As above, so below;
4. There are no coincidences;
5. There is a choice that is no choice;
6. Change is the only constant;
7. Seize the day and there is a price to pay;
8. A true magician must transcend himself.