The usual recommendation for keeping a dream journal is to keep a notebook and pen by your bed, and write everything you can remember right when you wake up. For several reasons, this never worked out well for me. Finding I'd written a bunch of gibberish in the middle of the night (if I could even read it) was a common problem.
So, instead, I keep my dreams recorded on the computer. Hanging around a bit on the computer is always the first thing I do in the morning, so the dreams are still fresh, and it gives me enough time from waking up to actually be able to clear some of the morning fog and really remember details of my dreams.
One of the big benefits to this is being able to edit what I'm writing easily. If I'm half way through describing a dream and suddenly remember something important from the start, it's no problem to add it in. I'm also able to add in keywords to the end of my entries, I like to keep track of who is in my dreams, where they take place, what time of day, animals, odd weather, and so on. I also mark common themes like being chased, flying, teeth falling out, or finding myself back in school. Having these keywords helps me to pick up on patterns and the like.
The draw back to journaling on the computer is if I wake up from a dream in the middle of the night, I have to get up and get to the computer to write it down. Truthfully, this isn't really that bad for me - I tend to wake up and sit up for a bit once or twice a night anyway.
Personally, I don't think most of my dreams are very significant. While I take an interest into patterns that emerge across many dreams, I don't really try to find meaning in each dream I have. For the most part I just see dreams as the subconscious unwinding a bit, and while there's certainly value in communication with your subconscious, I don't think every little thing is an important message.
For me the messages come more when I do see patterns emerge, or when I have recurring dreams about the same thing. Occasionally I will also have a dream that just... feels different. Very vivid, and it really sticks with me through the day. I do like to take a bit of a closer look at such dreams.
Additionally, I record my dreams each morning because remembering dreams is something of a skill - if you don't practice, you won't get better. That can lead to forgetting the important dreams on waking...
As far as actually interpreting dreams goes? A lot of people like to look to books, or ask others for help. While it's nice to brainstorm with other people on occasion, the best person to interpret your dreams is really you. It's your mind. Your subconscious. It doesn't matter if a book says X means Y when it means something totally different to you - go with your own gut on such things. Even if you think the dream is a message from a deity or a spirit, which does happen, that message is meant for you. You are the best one to decode it.
As an example, several years back I had tons of dreams where my teeth would fall out. At it's worst, this would happen almost every night. It got to the extent that as soon as it started happning, I would know I was dreaming, and would wake myself up (to count all my teeth). Everyone had a lot to say about the symbolism of teeth falling out... but I knew why I was having those dreams. I was having a lot of problems with my wisdom teeth, and getting them removed, and the whole thing was a big mess, and the whole idea of having this surgery (I had to be awake for it) was really scary to me. After that whole thing was over? I stopped having those dreams. It wasn't spiritual, it wasn't symbolic, it was just my mind dealing with the stress and fear of what was going on during the day.
Likewise, a current recurring dream these nights is being covered in honeybees. I believe this is a very specific message from Artemis. However, someone else having a similar dream might find totally different meaning in it. (Or maybe they're just scared of bees and are having a nightmare.) That's why it's important to really give a personal look at what's happening in your dreams. Which is not to say it's always easy to do that, but it's worth it to take the time and
meditate on the symbolism yourself, rather than just going with the stock
answer. Things become a lot more meaningful that way.