I thought it was necessary to create a post with a little bit of information that could be important for you before you start. If you're in the fence, this should help you decide.
Dreadlocks, to begin with, can be a lot of work. They're going to do what they want to do and if you try and fight them, well... good luck with that. I'll elaborate - every set of dreadlocks is different, you can get dreadlocks, but you cannot get dreadlocks identical to a musicians, celebrities or friends set. It's just not possible. Everyone has different coloured hair, different thickness, curly, straight etc etc. You have some control over how fat they're going to become if you start with a method other than the neglect method. (If you go neglect then the only thing you can do as far as shaping them is ripping the strands apart to stop huge dreads forming). So, you know you don't have as much control over them as 'normal' hairstyles, as they're going to lock and grow however gravity and various frictions deem fitting.
After you've started they are going to be MESSY. 'Tidy' tight dreadlocks take time to acquire and I mean TIME. On average you're going to be looking at an easy 1 year+ before the locks start to mature and knot/lock up by themselves. The only thing I can recommend here is to grit your teeth and bear it. You can wear hats, use headbands or tie them back (if they're long enough), but you won't be able to escape the fact that you've got loose hairs, tips and roots and that there isn't a huge amount you can do about it. See my Loose Hair, Roots and Tips post for more information on this. So yes for the first year to year and half you're going to have a bit of a birds nest / rats tails, BUT once they start to mature and lock up, well then you can relax a little because your patience will have paid off and they will only continue to mature and tighten more and more!
They take a long time to dry. Each dread is like a little sponge and so they soak up water and cleaning them will involve squeezing them out and drying will also require more of this. The dry time is also obviously much longer than with normal hair. How long depends on the thickness, length and maturity of the dreads. More on washing and drying HERE.
Dreadlocks can also affect some hobbies and activities. More info on that HERE.
But..... dreadlocks really are a get up and go hair style, the extra time lost in washing and drying is more than clawed back when you consider the hair doesn't need brushing, straightening, conditioning.... you get out of bed in the morning and it's good to go. When they're young and messy you can just tie them up (if they're long enough you can tie them back with themselves!) and get on with your day.
Dreadlocks are a fun process, there are active online communities full of like minded dreadlocked people. Unlike with most things you do to your hair dreadlocks don't wash out and once they've gotten going they just get better and better, so you can make picture timelines and really see how they're progressing, getting stronger and longer.
Once you've got dreads they're cheaper than 'most' other hair styles. You buy just one shampoo or soap or bicarb... or whatever you choose to wash with and that's pretty much it. No expensive shampoo and conditioner combos. No expensive trips to the hair salon etc. Once the dreadlocks are left to mature they will do their own roots and tips and will lock in the loose hair by themselves, completely free.
Also, to set your mind at ease - dreadlocks don't attract bugs like some myths would suggest. They aren't inherently dirty (they're as clean as you make them). You CAN remove them without shaving your head.
Other things to consider are the various negative and usually false stereotypes that accompany dreadlocks which get tiresome: No I'm not homeless, I probably wash my hair more often than most, I definitely shower as often as anyone else, I don't listen to reggae, I'm not a stoner, I'm not uneducated - working towards a Physics degree, etc etc, you get the picture.
Still interested?! continue onwards to the Starting Dreadlocks section to choose the method of starting dreadlocks that suits you best and the Preparing for dreads section to get your head and hair ready for dreads!