|I think most people who make anything funk, breakbeat drum & bass, or hip-hop would agree that 'Swing' is crucial to the effectiveness of a beat. The other key factors in a programming sense are 'dynamic' and 'accent'. So many people get wound up when their beats sound 'sterile' or mechanical' this is due to the fact that computers and sequencers lock to perfect BPM. A computer on it's own does not interpret rhythm the way a good drummer does, There are however, certain machines that have their own swing parameters like the Akai MPC range of sampling drum machines which are used extensively by hip hop producers.
Swing is not the easiest thing in the world to analyze but as a general rule good drummers will play slightly late and that's why in all funky records you get that slight dip at the start of the bar, take 'Superstition' by Stevie Wonder or 'Billie Jean' by Michael Jackson, these are both very simple beats, 'Superstition' is of course live drums whilst 'Billie Jean' was programmed but no less funky than 'Superstition' I emphasize this point to demonstrate that a programmed beat can be every bit at groovy as a beat played on a drum kit.
Expanding on the Billie Jean point, Hip Hop beats are really very simple. If you listen to the Neptunes they tend to create the swing in their beats by quantizing the kicks and snares and playing the hi hats in by hand, this creates a very tight beat which is off set by a loose hi hat, try it works, but don't forget your accents - As a starting point just take the first snare of your beat and turn the velocity down, then notice how your head starts nodding and your foot starts tapping a little more, you are giving the beat feel. Also remember that if you are using reverb the louder snare will push the reverb harder than the soft snare so your creating more ambience that way. Then try your kick drums, if your not sure which hits to adjust just pick apart a beat your feeling, I remember me and friend picking apart a Gangstarr beat and were able to almost replicate it by adjusting the velocities of each hit (admittedly it took a while to get it right!)
If you're a newbie then a common trick when learning to make good grooves is to create a template with an existing loop. The idea is take a loop you like that's got a good feel to it and then place your own hits over the break, then take the break out and see if your hits are sounding funky. This can take a while and it's crucial to think about the strength of each hit, or the 'dynamic'. Each kick will not be the same strength nor will the snares or the hats, pick the loop apart, dissect it and you'll soon see that there are certain consistencies in all good beats.
If you're using live loops and like to layer them with drum sequences, you should be thinking about time, space and frequencies. So if you have a fairly heavy loop then layering it with heavy kick drums is probably not gonna sound good. Think about filling holes, are their any frequencies that could be filled up? Or is there space in the loop for extra hits? Try working in layers just adding one hit at a time, also filtering works well, you could take some of the frequencies out of your loop as you drop your drum sequences in to make room for them. I think one the masters of this technique is Liam Howlett of the Prodigy. He runs breakbeats and gives them extra balls by laying a kick drum underneath to add extra intensity to certain passages in his set, but he's careful not to overlap frequencies to much. A good place to start if you using breakbeats is the Roland Tr-808 kick drum which is around the 50hz mark, which is sub bass territory so it will sit underneath most breaks very well.
If your hell bent on making killer beats and loops, then perseverance is crucial, keep at it, it will come together, listen to beats you like and pick them apart, identify the subtleties that make it happen. I know some producers get fed up when their beats sound to clean, or they are trying to create a new breakbeat and then compare it to sample they took from vinyl and get down on there own beat. Think about what a breakbeat really is, think about its history what has happened to it to make it sound the way it does. I'm sure you've noticed how some breaks have a certain something like a magic dust you can't put your finger on. Let me share what I know with you about that.
Most breaks, though not all, are taken from recordings of live drums, some of them are pretty old, so you have the ambience of live drums and the room they were recorded in, you have the fact that natural decay and reverb of each drum is likely to have bled into the other mics on the kit, and that most engineers used overhead mics which pick up the whole kit with two mics. Then consider that many of these breaks will have been recorded to analogue tape with saturation which will create extra warmth and harmonics. The next step comes from old sampling technology like the SP-1200 and the Akai s-950 / mpc -60, these samplers sampled at 12- bit (bear in mind that most computers now are at least 24-bit if not more) and that the samples themselves where taken from vinyl and on and on the process goes, with each new reverb and eq adding more and more to the break. In terms of giving your breaks that character there are a number of things you can try, for example buying an old four track cassette machine to dump your beats onto then re-sample it, if your using a sampler like the s-950 then try pushing the input meters a little harder than usual add reverbs and resample it, each time you put your loop through a new channel you will be adding something to it. Also distortion is fantastic for breaks, if you have any amp plug ins then try them, the Amplitude one is particularly good, you don't need to go mad with it just used subtly it works great.
To finish I would just like to say again, stick with it keep trying, keep listening to records, if you like to read about technique then do so, you can learn so much from other producers. Remember the strength of your hits is important as is the way it swings, good luck!