If the exterior of your house is going to get painted, it's important that you make sure that it is appropriately prepped. Prep work is very important for any paint job. That's because paint can have a hard time adhering to an inappropriate surface.
Get a Flat Surface
Before you start painting, you want to make sure that your surface is as flat as possible. That means getting rid of anything that could be an impediment to painting the full wall or anything that you would have to be careful painting around. That means things like shutters, mailboxes, flower boxes, and house numbers. All of those things should be easy to remove. You could replace any screws that don't look like they are in good shape at this time too. Otherwise, you should keep all the hardware in a resealable baggie and attach it to the item with tape so it doesn't get lost. You may also want to take pictures because that will help you put everything back the way it was.
Get Rid of Flakes
One of the worst kinds of surfaces for a new paint job is one with paint flakes. The new paint will adhere to the loose flakes. Then the pre-existing flakes will start to fall off, and that will cause the new paint job to look bad. Getting rid of all the flakes is going to take some work, but the results are going to be worth it.
What you are going to have to do is get a paint scraper. The broad blade will let you get a lot of coverage. You may also be able to find a scraper that has a narrower surface that will let you get around the corners and edges better. If you have wood siding, it's important to make sure that you are careful when you scrape the flakes off. Make sure that you hold the blade perpendicular to the wood, that you keep the blade flat to the wood, and that you use moderate pressure. You don't want to damage the wood while you are getting ready to paint.
Making sure that you do what you can to get a good canvas before any paint goes on the outside of your house will help you get the best results. If you don't feel like it's something you can handle, you can hire a painting company to learn more about this topic.