For short domains such as 4-letter domains, before you do anything, you have to decide why you are buying the name. What's your overall purpose? This will determine which names you should buy and how much you should pay.

I can think of the most obvious reasons for buying these names. This list, though, is far from complete. There are almost endless possibilities when buying domains, and countless reasons for buying one. Every domainer has their own game plan.

1-For use in your business, or for personal use.
This means that you are the end-user. Try not to let any seller know this! Some sellers will see this as a reason to ask the moon for the name. Depending on how vital the name is to your business, it may even be worthwhile for you to pay the moon....but that's no reason to hand out easy money. For our purposes, with LLLL domains, we are probably talking about a brandable word, such as FIXR (no, not one of mine), or an acronym, such as N.A.S.A. (unfortunately not mine either). Four letter keyword domains are all priced in the stratosphere. You will never see one on Ebay unless it's some tricky guy using a zero to look like an O. (As in H0PE.COM). Watch out for that trick!

Obviously, not I or anyone else can tell you which is the best name for your business. If you're lucky, it's an unpopular acronym such as XJYI.COM, or something like that. As long as you don't reveal that you are an end user, or that you have development plans for the name, you should be able to get that pretty cheaply.

2-For investment.
 In this case, you don't plan on selling the name until maybe a year, or even several years down the road. Your options are pretty wide open here. Most domainers will tell you to concentrate on a few quality names rather than 100s of lower quality names.

That's generally good advice.

The problem, though, comes in how you define "quality." For most domainers, the letters XYZJQ are seen as anti-premium, and KUV are seen as non-premium (or something like that). In fact, the evaluation of letters pretty much mimics the points given to Scrabble letters, only in reverse. Since Scrabble points are based on how rarely a letter can be used, it makes a bit of sense. You are hoping that the LLLL can be applied to a larger number of acronyms. But here's the problem with that:

a) Scrabble letters are based on usage anywhere in a word. But for an acronym, you only care about letters that form the start of a word. You'd be better off counting the number of pages devoted to each letter in your dictionary. But even that will only get you so far. Some words are used very frequently in acronyms, making their starting letter more valuable. For example "corporation, organization, etc.

b) These valuations are mostly based upon English demand for the letters. However, and acronym can be applied to any language. This is one of the strong points about acronym domains vs. keyword domains. X, Q and Z are all widely used in China, a country with a population 3 times that of the US. Get my drift?

For non-acronym domains, such as those that are pronounceable and brandable, you'll pretty much have to use your own intuition and hope for a bit of luck. The web is open to all kinds of alternative spellings, and you might get lucky.

3-Domain reselling - Hey! That's my job!
And it's not as easy as it looks. However, if you can't resist, come one in. Only experience will teach you which names you can sell for more money right away. And even then, luck plays a part. Your great name might go for dirt cheap. Your dirt cheap name might go for a bundle of money. My only advice there is don't buck the trend. Buy what you know you can sell for at least what you paid for it. Search Google to see if you can find something in the LLLL that others missed. If your LLLL is ABCD, you should search all these terms:

abcd
"a bcd"
"ab cd"
"abc d"
abc +d
bcd +a

And probably more. If you find a great name, and get it for a great price, then sell it. Do not ever get attached to your names if your plan is to resell. If you love it that much, develop it into a website. If you're not going to develop, and don't have the spare cash to sit on it as an investment, then just sell it.

For all LLLL.com buyers, you can benefit from checking Ebay at odd hours. Also look through all domains, not just those marked as LLLL. Some sellers don't know how or when to list their names. If you find those listings, there's usually a bargain to be had.

Any other ideas? You'll need them, because there's competition out there. Good luck!