"Okay" you're saying. "My surroundings need a little doom and gloom, but I'm at square one, what do I do first Aunt Bat?"
     The first thing you need to do is find a focus. Start small.  If you're trying to "Doom" an entire house or apartment then it is best advised that you pick one room and start there. If you're more of a "social-goth" and often have friends over for
gatherings or parties, then you will probably want to start with your living room. (or den, or reliquary, or abattoir ... You know, the room you entertain in most often.) I would then move on to other rooms that company would be likely to use or see, like the kitchen or the bathroom. Bedrooms and private spaces can come later.
     Or, on the other hand, perhaps you are the type of person who does more, shall we say... "private entertaining"? In that case you would want to start with the bedroom. This also applies if you are really anti-social, or maybe your bedroom is the only space that's "yours".
Once you have decided what room you are going to decorate, we move on to picking a theme.

     The easiest (and most obvious) would be your favorite movie or movie genre. For instance, if you're a big fan of Tim Burton you may want to
include black and white stripes (or some other recurring visual element from his films.) Or, if you are a big fan of the old Universal horror movies you could use the advertising posters from those films. (reproductions of course!)
     You can also let your closet be your guide! Let your taste in clothes influence your décor ~OR~ decorate in a style that you're not able to wear because your income/body/job etc. is all wrong for it. For instance, you may want to decorate in the  victorian/romantigoth style, because you have a "t-shirt and jeans" kind of job. Simply explore the
romantic, ultra gothic side of your personality in your surroundings!
     Another suggestion in choosing a theme is to look through catalogs and magazines and compile a file folder of pictures. If you're not sure what you like specifically then just browse and pay attention to what catches your eye. If you find that as you go through catalogs and magazines you are pulling out and saving pictures of candles, then it's probably a safe bet to go buy a few. Likewise if you find yourself saving pictures of lace curtains or sleek modern furniture. 
     Finally, don't let yourself be stifled by the word "Gothic". If you see something and YOU like it, go for it! You are the one who has to live with your decisions, so make the right ones for you. 

   1. Invest some money in one or two really well-made items. If something is "cheap" it's going to look "cheap" and chances are it won't hold up. You're not saving money if you have to  keep
replacing the same item again and again.
    2. Pick a theme and stick to it! This is the
easiest and most effective way to avoid throwing away money on things that may just end up in storage, or in the trash.
     3. If you've carried it around the store for 20 minutes trying to decide if it "goes" chances are, it doesn't. Put it back.
    4. Let Fate hold the purse strings from time to time. If you see an expensive item that you MUST have, wait. If you go back for it and it's gone, it was not meant to be yours.
    5. Before you spend a dime: DO YOUR
RESEARCH!!! Shop around; look at pictures in magazines and books. Keep a folder for pictures and ideas that you like, and refer back to them
often.  Use these sources as your guide and your shopping list. (and stay organized!)
     6. The craft store is your friend! (in other words kiddies, don't pay $40 for the six inch "resin" gargoyle statue when you can pay $2 for a plaster one that you can paint yourself!)
     7. Above all else, be confident in your own
artistic abilities and don't be afraid to experiment!