I need help with my gutters!

Hi everybody! My property recently suffered some roof and gutter damage, and I need some advice on how to proceed. It all started a couple of weeks ago during a very strong rain. I noticed that there was no water coming out of the downpipes, even though the rain was pretty heavy. After the rain was gone, I looked up to the roof, and noticed that the water pours from the top of the gutters. Turns out that the whole system is fully clogged, thanks to the trees surrounding the house. I wanted to clean it myself, but it’s a two story house, and my neighbour told me that it would be too dangerous without special equipment. Then he recommended me to call some company to unclog the gutters and clean them. He recommended this one – http://www.paulsguttercleaningsydney.com.au/ and I also found this one – http://www.nationwideguttercleaning.com.au/ while I was researching the problem online. I seriously consider calling such a company and have them deal with the dirt inside the gutters. But the bigger issue is what to do next in order to avoid such situations. Do you have any idea how can I do that? I read something about gutter guards, but I’m not sure how they work exactly. Is there anyone in here with experience with these things? I personally would like to know if the gutter guards are so efficient as they say, will it protect my gutters from the dirt, and will the water still be able to flow in freely, or it will overflow and damage my walls? Also, if you know about any other reliable company which cleans such things, please send me information so I can check them out. I would be really thankful for all kinds of advice on the topic!