One of the issues that people have when they are looking for free beats and free instrumentals is that the quality of the free beat and instrumental can leave some things to be desired. The beats are typically either a good idea that is poorly mixed and poorly engineered or really bad generic ideas that are engineered real well. Or of course they could just be bad ideas with a bad mix. Either way they are probably not something you are interested in using in your project. You would be better off making your own beat or using an industry beat. So what should you look for in your free rap beats and instrumentals? Probably the same things you would look for in a beat you would have to pay for.
Drums, do they snap? How is the snare sound? Is it crispy and clean just like it should be? Or is it muddy, maybe too much of the high end is rolled off, or maybe the sound is just a bad sample of a snare sound. Then how is the kick sound? Is it deep and is it going to hit in your car when you turn the sub on? Or maybe is there too much bass. A lot of times producer tend to overcompensate for a poor mix or maybe even a poor beat by adding too much bass. Now how do the hi-hats sound? Are they clean and crispy like the snare? One of the problems that I always find is that the hi-hat sound is typically to high in the mix.
Next how is the intro to the beat? One of the things I have noticed to be extremely important to beats and also a challenge to me is making the intros to my beats more than just the instrumentation without the drums and then having the drums come in to signify the start of the song.
What is the melody like? Is it catchy? When you think about a rap song you are thinking about a song that is carried by vocals that have no melody just spoken. So typically the melody comes from the beat. This is a good thing and you should try to find a beat that has a catchy melody within it.
How are the sounds that were used? Do the strings sound like they came from a cheap Casio keyboard? The thing with these cheap sounds is that sometimes they can be used on purpose and sound real cool. Typically though the sounds used be new producer sound cheesy and that is just because the producer does not know what to do to make the sound actually sound good.
If you think about these things when you choose your free beats and instrumentals you should have better luck. Obviously the most important thing to do is just use your ears. If you like it than you probably like it for a reason. You might not know why but if you like it I am sure that other people will like it as well.