Arrange your hip-hop beat by laying a drum sample first. A beat is the music of the hip-hop song without the vocals, and the instrument that holds it together is the drum. Insert a drum sample or audio loop. This could be as simple as a bass drum kick and snare repeat or as complex a whole kit combination.
For example, to arrange Eminem's "Crack a Bottle" lay down a looped bass drum kick in a hit, rest, hit-hit, rest arrangement and add a floor tom drum hit on top in exactly the same way to match. This is one bar of your beat. Insert a snare hit in every rest of the bar and copy and paste it over 4 bars; then add a cymbal crash to the very end of every 4 bars.
Mix and change the drum beat for the different sections of the track. This is important because it gives variety to your beat and will help maintain a structure to your song. For example, change the tempo and drum sample of the chorus section. Do this by adding a snare roll or extra bass drum kick to the end of each beat bar and perhaps slow down the tempo to show a shift in song's structure.
For Eminem's "Crack a Bottle" create a new beat bar that runs two kicks of the bass drum in a hit, rest, hit and rest. Add on top of each kick, add a cymbal crash. This is very a basic setup for the chorus, but still adds variety to the track.
Add any further instrument samples and match them to the existing drum beat. Traditionally, hip-hop beats consist of drums, bass and orchestration (synth, strings or horns). Add similar samples of the chosen instruments and match it to the tempo and style of your drum track.
For example, on Eminem's "Crack a Bottle," add a synth keyboard that is programmed with a horn section sound. Play an A and C# chord for two beats and then an Ab and C chord for two beats to make a 4-beat bar. Add a 4-beat bar of complete rest and then repeat the structure to make the verse's synth.
Arrange the different sections and lines of instruments into a complete song structure. Although you may already have a verse and chorus beat mapped out you still need to arrange the track as a whole. You might consider arranging a simple verse, chorus, verse, chorus structure, or a verse, verse, chorus track.
Arrange Eminem's "Crack a Bottle" in a chorus, verse, chorus, verse, chorus, verse structure. Remember this is only a sample song; take what you learn from this track and use it to experiment with your own original songs.