If you are planning on painting your own home, you should recognize that there is a lot of work that goes into getting that accomplished. The prep work you do before you actually paint is typically 40-60% of the overall effort, so do not underestimate it!
One of the first things you need to do is pressure wash your home. There is a lot of dirt and mud that build up on a house over time and you do not want to apply a fresh coat of paint and lock in mildew and dirt. So pressure wash your siding thoroughly and make sure you get it good and clean. Before you pressure wash check the seals on your windows to make sure you do not have a leak. The last thing you want to do is start pressure washing and have a ton of water come through your house and flood it.
If you have older cedar siding, then there is chance that you need to sand it down and get the wood flakes off. A great tool for getting the cedar siding smooth is to use a sander or hand sand it (although that takes quite a bit of time) and the goal is to get a reliably flat surface that you can apply primer and paint to.
Another critical step is the masking. You need to make sure to mask off the windows so that you do not get paint on the window. Also if there are cars nearby, put a tarp over them. Getting a bunch of paint flecks on a new car would be expensive to fix, do not do it!