There are many different types of kick drum samples available for music producers today. Beat making is such an involved activity that having to use the same samples over and over can really kill your creativity. This is especially true with kick drum sounds as these are an elemental ingredient to just about every rhythm and blues, hip hop, rap, pop and rock song on the charts and underground today.
A kick drum sample has a few phases, the first being the start or attack. If the attack is very strong, you will be able to hear the introduction of the kick through many other instruments and sound layers, and if it is not that strong, you will still feel it but not be made aware to its presence immediately every time . Rap music producers (and others, too) often use compressor tools to really spike up the start of kick and snare drums, and this can be a powerful choice for drum-centric tracks.
The sustained sound of the kick is very different depending on the type of sound that is chosen. One of the more famous sustains can be found in the sounds made by the famous TR-808 sampler and synthesizer by Roland. It has a very long booming sound that degrades in volume with time and yet keeps everything moving. The TR-808 actually has kicks of varying lengths for different applications, too.
Adjusting the volume envelope of a kick drum sample is very easy with the right tools. Most samplers will include an envelope modifier for the volume or can be modified to do this very easily. If your drum sampler or sequencer does not permit this, look for some free tools that will help you; there are literally thousands of free virtual sound generators and effects plug-ins available on the internet for free personal use.
If you still do not want to use an envelope to modify the volume, it's very easy to do it with an audio editor. Just select the part of the drum sample wave that fades out or stops (the end of it) and trim to your liking. To blend everything in after a crop, use a fade on the last few milliseconds to ensure that the drum samples are free of clipping.
Lastly, you should know that different programs include different drum samples. The libraries that ship with Reason and FL Studio, for example, are vastly different. They are both good, but if you find yourself making beats with the same drum samples over and over, look for some expansion packs or third party sounds to expand your choice, or modify the samples yourself if you have the time and skill.