I've decided to write this up for people here at DDBoard. Feel free to add to it.
What are reputation points?
Whenever you make a post, depending if it's a good or bad one, any user at DDBoard has the ability to make you seen as a better or worse member here at DDBoard. They can give you a positive reputation point or a negative one.
Why is this so important?
Many members will not trust you if you are not well known at DDBoard or have a bad history. So this will make it hard to sell your points, domains, websites, or even buy from members. Having one or more small red blocks near your rep power below your username is a big warning to other members on first sight- "Don't have anything to do with this user!"
How do I add a reputation point?
If you're logged in, at the bottom left of each post you should see a star. Click it and you can give or take away from that user's reputation.
MAKE SURE YOU TYPE IN YOUR REASON! How do I check my reputation points?
If you're logged in to your account, at the bottom left of any of your posts, click the reputation star and it will say how many reputation points you may have earned and how many you have overall.
To check the latest reputation points that have been added or taken away to or from your account, go to your User CP and scroll to the very bottom until you see the reputation section.
How many reputation points do I need to gain in Rep Power?
To add to your rep power you'll need 10 positive reputation points.
A better and more complete guide on reputation by multippt here. Thanks multippt! Tip 1: Proper English.
I know that a lot of people at DDBoard can't speak English fluently and it's hard for them at times, but try your best. I'm sure you know when to use apostrophes, periods, commas and capitalizations when it's time to use them. It's okay if you make mistakes, but don't be careless. Don't take the quick way out! Using proper English makes your posts more professional and seem longer.
Tip 2: Don't ask people for +rep.
I've done this before, I'll admit (tip: be honest :]). At the end of a post, don't add "Remember, +rep if you like a post!". Add that to your signature, not your post. The person will rep you if they want to! It's annoying, and can be rude, because maybe they didn't feel that you deserved it or something. And another thing is DO NOT PM people for +rep and spam them. I'll report you if you do that to me and you'll be on my bad side.
Tip 3: Don't spam.
This includes thankyou's, bad website reviews (i.e. "this site looks good"), website errors when posted ONCE before (i.e. "your page is down") (I can't tell you how annoying this is spamming for points. People SUBSCRIBE to threads to see that bloated crap you're posting), flaming, and basically any bad post I'd categorize as spam.
Tip 4: Show care in your posts.
It's rude to some people when they see posts in their topics that are a couple of words and random things added to reach the character limit, and annoying to many others. Make your posts long and put thought into them. Also, make your posts easy to read because having them not being able to easily read won't result in a +rep. Use the normal font size, don't change your whole post's color from black to something else for no apparent reason, and dont change your font and use bad combinations, like using Arial Bold and then bolding your text again. It's hard as hell to read and annoying. If you do this and your post is actually really good, a person will probably not give you a +rep because of the annoyingness.
Tip 5: Be helpful.
Be helpful to the DDBoard community and post links you come across that helped you. Help others with problems they have. There are many things to do to help. You can post some suggestions or bugs you see in DDBoard. This won't benefit you, no it won't give you extra points or domains, but to it because you can.
Tip 6: Good topics.
Step 1: If you're making an informative topic, search if the topic wasn't made already.
Step 2: Think of where to place the topic. Don't ask for website reviews in the member advertising section, and don't put so many topics based on different sections of your website in the advertising section or the review section.
Step 3: Post with good thought. As the topic starter, you need to show you made this for discussion and not for DDPoints.
Tip 7: Post count isn't everything.
In any forum user, I look for quality posts and reputation points. I don't look for the post count. If I see a user with a high post count that joined a couple of months ago I assume that they don't put thought into most posts. I'm talking about thousands of posts. So stop emphisizing your post counts!
Tip 8: Don't overprice.
If you're selling things or offering services, don't overprice. Don't sell 2,000 DDPoints for $8 USD and try to rip off a member that doesn't know any better. This will add to your reputation, sure. I'll decrease it if I know you know better.
Tip 9: Be funny.
Don't overdue it, but being funny makes a post enjoyable thus leading to a +rep. Don't post any perverted or disturbing jokes.
Tip 10: When making lists, make them in multiples of 5 or 10.
It makes them look cooler.