Avoid extraneous time-based effects like reverb, echo and delay. While these types of effects can create an interesting feel for certain songs, in many cases these time-based effects can cause music to feel like it's not in sync. This is particularly true with drum samples that you or others have created. As a general rule of thumb, if it feels like your beats are swimming in effects, make two mixes. Make the first one with the full amount of effects, and then cut the effect volume in half for the second mix. Take a few days away from the song or beat, and then listen again to decide which mix you prefer.
Edit analog tape loops so you cannot hear the transition. A very common way of doing this is to make your edit during a continuous sound that starts and ends the particular sample. In many cases, this is a high-hat, ride or crash-cymbal sound. Once the music is mixed, you will most likely not hear the edit, and it will give you a little bit more freedom when splicing analog tape, which can be a difficult procedure.
Play any live drums to a click track that is the correct tempo all the way through. In some cases, songs speed up or slow down during a chorus or bridge. If your song does this, make sure that you change the tempo of the click track in those parts. This does require a bit more time for mapping out your song and counting beats, but it is well worth it, as the finished song will be much tighter and have a stronger groove. This can be particularly important for some types of music.
Avoid editing numerous drum tracks together to make one track unless you are replacing hits with a drum machine or drum replacement software. While editing some parts of a live drum set can work, if you are using an extensive microphone setup, compiling multiple drum takes into one track often sounds sloppy to listeners. Of course, if you need to replace one snare hit in a song that is otherwise perfect, you can do that with little consequence. However, making multiple edits will often sound a bit off to the average listener.
Use time-altering software like Serato's Pitch 'n Time if you need to alter the tempo of any portion of a live or pre-recorded drum take. While you may be able to manipulate portions of a song by hand, programs like Pitch 'n Time allow you to move parts of a song while accounting for human error, which is essential when altering a beat created by a person instead of a machine.