How difficult is it to adopt a child (single man, 29 years old?)

It kind of depends if you are planning a domestic or international adoption. Most countries outside the US have minimum age requirements of 25–30, just depending on the country. Some countries will not allow a single male to adopt.
The US infant adoptions – while legally you can adopt at 18/21, most agencies are pretty strict with their requirements too. Mostly I see 25 being the minimum age, and they prefer a few years of financial stablility to consider you as a prospective parent. Doesn’t mean you have to be rich, just means you have to have a stable consistent income.

If you are considering adopting a child from the foster care system, I think a lot of states have an age of 21. But again, they’ll want to see the financial stability, emotional stability etc.
As for resources, it would help if I knew what type of adoption you are thinking of doing. There is a ton of info out there specific to domestic, international, fostercare etc., so helps to narrow it down.
http://www.adopting.org/adoptions/learn-about-adoption-who-can-adopt.html

Being adopted myself, I can tell you you’ve got to be financially healthy, like @MrGeneVan mentioned.

Outside the United States I think is more costly (like me) usually $20,000 + not counting the legal paper work etc.

Sadly, the fact that you’re single and a man will play against you, making it even more difficult than usual for you to adopt. It shouldn’t be so, at all, but it is and it sucks and I’m sorry.

Maybe you can start the process now, but at the same time, try a big brothers type of program. That sucks that there’s so many people like you who want a child, and there’s so many bad parents that don’t want or deserve a child.

Are you thinking about a baby or would you consider an older child?
Try fostering first, that way you definately know you want to have a child, entering into adoption isn’t something that should be taken lightly. Good luck with your endevours and remember to talk to someone you trust and respect before you make this decision, couples have the luxury of being able to discuss their hopes and fears with each other, it may mean you have to wait a bit longer but better to be sure now than 6 months down the line when the child is involved and emotionally attached.