I often make hip-hop beats for my rap and free-style friends. When I first start out creating a hip-hop beat, I study the rythym from groups like Three-six Mafia, Twiztid, and the darker, more undergound lot (cuz 3-6 has some bomb-ass beats) or even Bustah Rhymes; those three are very different styles.
Tip 1: Verses
The beat is made based on how the verse will be spit. Say they want to rap fast, yet also make it seem faster, make the bass hit slowly in the beat (for example Mystikal); or in the case where they want to spit 2-5 word patterns, speed up the beat giving the vocal more intensity (as done in many DMX tracks).
Tip 2: BPM
The range I have found works best is anywhere from 83 - 113 BPM. Keep your rhythym within that range.
Tip 3: The Beat
You can take a simple DNB break (Entity's "How to" on DnB Beats)and slow it down; then add some kicks and snares to add to the groove and fill up space in the lower tempo environment. Remember to add variation with the drums because in general, hip-hop beats are pretty damned repetitive! Also add some claps and hats to supplement the overall groove and rhythym. Feel free to experiment with other percussive sounds and perhaps some backbeats, etc.
Tip 4: The Bass
Add a nice bass groove should not be too difficult. Try a sub-808 sound and loop it (for FruityLoops users, use the CRF knob), then add to the piano roll (again for FruityLoops users) and experiment with the sub-bass groove over the drum rhythym. Make sure the bass and beat blend well together. Don't get frustrated, this portion takes a long time to perfect and requires some degree of musicality. For a tutorial, take a look at How to Create a Rolling DNB sub Bassline in FL Studio.
Tip 5: Ambience, Melody, Background Groove
The background is all up to you. You could go with the eerie classical approach (like 3 - 6 Mafia), the gangsta style jazzy piano (like in many of Mobb Deep's tracks), or even the hard rock guitars that have been used by everyone from Public Enemy to Esham and Twiztid.
You might want to have some strings, plucked guitars or other ambience. Remember, don't overkill the background; the main parts of a hip-hop rhythym are the beat, the bass, and the vocals. Melody is not really a necessity, but this doesn't mean you can't have one. With hip-hop, the star of the show is the MC. Don't drown him/her out.
Tip 6: Arrangement
When it comes to a hip-hop or pop track, it contains these basic segments within the entire arrangement:
The trick is, where do you put these parts and what do you do to each part to make it distinct?
Naturally, you would want to start with an intro. Then you bring the track up to speed and into the first verse. After that, change to the chorus. The chorus, or "hook", is where you have your catchy repeitition that will sell your track. It is often repeated several times in a track and often includes a pre-recorded vocal track that will be laid down into the instrumental. Like that Outkast song "Hey Ya" -- the chorus is the pre-recorded vocal singing of those words "Hey Ya"; over and over again. In other words, this part generally establishes the theme of the track. After the first chorus you may want to add a slight breakdown to the track and lead it into the second verse. The second verse should be slightly different in comparison to the first verse but should also maintain the same groove, theme, and rhythym. After that, add your chorus, then verse, then chorus, then close/outro. Be sure to add breaks where appropriate, depending on your musical tastes.
This is just a few tips for your reference. Feel free to ask me any questions via PM.