1. First, find a card or a combo you're crazy about. Saaay... Kokusho, The Evening Star.
2. Then head on over to the Gatherer: http://gatherer.wizards.com/Pages/Default.aspx.
3. Do a search for mono black in the Kamigawa block (make sure to hit "exclude unselected colors") Next I sort the results by "community rating" in "descending order" . We're looking for around 20 creatures and 8-12 other spells. I quickly see cards like Cranial Extraction and Rend Flesh, both very very good cards. Sooner or later I notice a few themes: Spirits and Arcane spells and also RATS!
YOU ABSOLUTELY WANT YOUR CARDS TO WORK TOGETHER IN CONCERT TOWARD YOUR GOAL OF KILLING YOUR OPPONENT.
Since I'm not a huge fan of Rats, I decide to go with Spirits.
4. Next, go to http://magic.tcgplayer.com/db/submitdeck.asp and register. Once you do that, click "submit a deck". Next select "Vintage" in the drop down, and enter in a name. I've chosen Nightlights for this deck because it's black and Kami always have these floating light things around them... plus nightlights is warning that there be monsters here.... Then start entering in your cards.
24 Swamp
4 Wicked Akuba
4 Thief of Hope
1 Kokusho, The Evening Star
4 Rend Flesh
4 Cranial Extraction
you'll notice that there are four of each card. I make it a policy to have four of each non-legendary spell. It helps to narrow down which cards are the absolute best for the deck. It also makes it a lot easier to swap things out during deckbuilding and between your sideboard.
5. We continue the quest for good cards. So we're looking for spirits and arcane spells with good ratings. Read the discussion behind the cards to see if there are combos. I notice there are a lot of legendary spirits. Funsies! That'll mess up our 4 of each plan, but that's OK. We see some interesting abilities like "Splice onto Arcane" . We'll try to use these to our advantage if we can. So, just keep finding cards you like and adding them to your list. Try to find spells over a change of costs. You want your average cost to be around 3 or 4 depending on the deck. Removal is essential, as is one really good utility spell.
Here's what I have so far:
24 Swamp
4 Wicked Akuba
4 Thief of Hope
4 Kami of the Waning Moon
1 Infernal Kirin
1 Horobi, Death's Wail
1 He Who Hungers
1 Akuta, Born of Ash
1 Iname, Death Aspect
1 Kokusho, the Evening Star
4 Rend Flesh
4 Cranial Extraction
4 Death Denied
Having four of each card also makes them easier to count! But we have 54. We're missing 6 cards...
6. Now is when I go back to the search box and search for artifacts in this set. We see that there are 44 to choose from! Again, sort the results by community rating in descending order. Guess what's at the top! Right, THE Top. If you have one of those, go ahead and throw it in!
I try to stay budget with the decks I actually purchase, so, for this example we'll leave the top out. (Assume we already had a copy of Kokusho :P) You can always add the better cards later when you are able to trade for them.
Looking on down the list we find exactly what we are looking for! Long-Forgotten Gohei, which boosts our spirits and lowers cost for both spirits and arcane spells. We're going to want 4 of these. Checking through the artifacts I don't really see anything else we need, so go back to your list and add in your new prizes...
7. Once you have a full list of 60 cards, hit verify. Fix any errors and hit verify again. It's a good idea to just copy and paste names of cards from the gatherer so you don't have too much trouble here. On the next page you'll be able to see some interesting stats. First, our deck would cost around 40 dollars to put together. Not bad! budget decks are nothing to scoff at. Next, check out the mana curve. we see the average casting cost to be around 3 which is fairly low. That's good because we don't have much ramp except for the Gohei.
8. Here's where it gets fun. Hit "view sample hand" and see what cards you get. Keep doing this again and again and again to see if your first hands will be playable ones. If not, go back and tweak the deck.
Congrats! Hopefully you've created a deck that showcases some awesome cards in action. It might not win you tournaments, but it'll be a blast to play and you can be proud that you put it together from scratch.
If you want, you can create proxies (which are just junk cards that you write on to represent cards you don't have) and then playtest to see how the deck plays and if you need to make any changes. After that, head out and trade for or purchase your deck. You can use http://magic.tcgplayer.com/ or http://www.cardshark.com/ to find the best prices for the cards. Try to purchase from as few sellers as possible to minimize shipping.
Well, I hope that gives you a good start! Thanks for reading.