The process that goes into putting together a project can be crucial. As it can have an impact on the success of your career as an artist. Having a decent budget with solid production is the foundation of this process. Choosing the right beats that have chemistry with your sound. Is what makes memorable mix-tapes and albums. Knowing what direction you'll be taking and the message your project will convey to your audience is important. Creating a statement with your music that not only speaks for you as an artist, but for you as a brand. It all comes down to the beats you choose for your project.
The next time you come across a producers website and hear a few beats that you like. Try writing to them first before purchase anything. And if your inspired to write then use that as an indication to purchase the beat. You don't want to buy a beat that sounds great only for it to end up sitting on your hard drive for months. All because you failed to realize that the chemistry just wasn't there from the beginning. Leaving you uninspired to write to a beat that you thought would be a good fit. This can become costly over time if this is happening often. Think of it like shopping for clothes. When you see a shirt that you realy liked and tried it on. Only to find that you didn't like the way it looked on you. This same analogy can be applied to buying beats. You'll need to try before you buy if the option of "Demo Downloads" available to you.
Choosing beats that complement your sound and style are usually what will inspire you to write. There are a few things to take into consideration. When you're picking beats for your project. The tempo of the beat will dictate your approach. For example rappers that tend to have a fast pace flow will normally go for beats that have a slower tempo around 65-75 BPM. This speed allows room within each bar to fit more syllables. As the tempo increases the speed of a rappers flow will start to decrease. As for rappers who prefer Mid speed tempo's 85-95 where the pace of the beat is not too fast or too slow. And for up beat, party and club tracks will be at 120-140 BPM.
Using a websites search engine can help you narrow down your beat search tremendously. While this can be a time saver there are instances where some producers won't include tempo information. And may require you to have some knowledge of beat mapping to find a songs tempo. This can be done using your DAW. If your are able to download a demo of the beat your interested in.