Firstly, if you are going to aim high and shoot for those major labels you may want to read my post on how to contact labels . There is nothing wrong with shooting for majors, in fact it is the main thing you want to shoot for in order to make a career but im going to focus on what most of us release on; independent labels.
The fact is, 100s of tracks are coming out every week on beatport, so the chances of your music being lost in the wave of new releases is extremely high. With that said a good thing to look out for is what labels are regularly gaining chart positions / banner features / staff picks or featured releases on the genre's homepage. This is generally a good indicator for which smaller labels are gaining attention. Find a label who puts out similar music to what you make and keep an eye out on all the feature spots on beatport to see which labels are gaining frequent recognition. This will at least give you a higher chance of landing one of those feature spots if your music does make it on the label.
With that said, you should also take note of any of your favourite Dj's charts on beatport and scope out what labels they are supporting. Same goes with their podcasts. In doing this it enables you to get a general idea of the labels promotional lists. Big Dj's supporting your music is the best way to get your music out there and you ideally want a label who is regularly supported by some of those big names.
Another thing to pay attention to is the social media presence of the label. Ask yourself.....can this label really reach more people than I could on my own, or have I just signed over the rights to my master for nothing? Remember fans and likes can be bought, you want to pay attention to the interaction on their pages, see how many people are sharing their posts and talking about their music. Unfortunately a lot of small labels wont actually promote your music too well, so it is worth aiming for the ones who take it a little more seriously.
Finally for this post I want to talk about labels you are passionate about and believe in. See there are still lots of labels out there with great artists on and ran by great people but they haven't yet gained the right traction. But remember consistent good music will eventually be picked up. Personally I still release on a smaller labels and will hopefully continue to work with such labels because I genuinely believe in their potential, not only that but they are ran by serious and professional people and also have a roster of great upcoming artists. So yes do aim for labels that are going to provide lots of exposure, but don't neglect those labels you are passionate about and have built genuine relationships with. By the way the label I like to work with (amongst others) is Axon Recordings......check them out, some really cool artists and music coming from them. It is also based close to my hometown which makes it even more special. So involve yourself in a bit of both, aim for those labels where you may get support from bigger names and land those feature spots but also find labels which you believe in and can build relationships with people in the industry.
And if all else fails......become a marketing wizard and just release everything yourself! Remember, in this day and age an average track marketed well often makes a bigger impact than a brilliant track with shite marketing. That is the unfortunate truth.