Making mashups can be really rewarding. Nothing describes the feeling you get when you blend two songs just right to make a totally new tune. If you get good enough you can even start dj-ing parties and events. Here are some steps to get started:
1. Listen to Music
This almost goes without saying. You probably listen to music now, but if you want to create or remix music, you will have to step it up a notch. Start subscribing to music blogs, reading music news, and listening to everything you can get your hands on. Educate yourself on music genres, what is currently popular, and what your personal preferences are. Learning some music theory is good too. The one piece of theory you will HAVE to learn is tempo or "BPM" (more on this later). Keeping up with music and educating yourself is a continuous process, but once you get in the habit it is actually fun and rewarding.
2. Download Music and Keep it Organized
Unless you've been living in a cave since the 90's, you probably know where you can download some of your favorite music. You should be doing this already as part of step 1. It will really help if you keep your music organized. Organizing by artist doesn't help very much for making mashups, so it might be better to organize by genre or tempo. One strategy is to keep your personal music and your "mashup music" separate. That way you can organize them differently. Also, some of the programs mentioned below have organization features built-in. The organization method doesn't really matter as long as it works for you.
3. Download Mixing Software
This is what you will use to actually make your mashup. Popular choices include Ableton, VirtualDJ, and Serato. There are also many tutorials online for how to use most of this software.
4. Find Two Compatible Songs
In order for two songs to make a good mashup, they must have a similar tempo. Tempo refers to how fast or slow a piece of music is, and is usually measured in "beats per minute" or "BPM". Most mixing software will calculate the BPM of a song automatically. Rap is usually about 80 or 160 BPM. Dance/techno music typically works the best and is around 130 BPM. Try to find two songs that are less than 10 BPM apart.
5. Mash It Up!
In order to make a mashup, you will need to make the BPM of song A match the BPM of song B. Load both tracks into the mixing software, and adjust the tempo of one song so that it matches the other. Next, line-up the first beat of song A with the first beat of song B. Finally, start the songs playing at the same time. Now you have a mashup!
Sometimes you need to adjust a song while it is playing to get the two to line-up just right. Most mixing programs show the peaks and valleys of the sound waves that are playing. Try to line-up the peaks of song A with the peaks of song B (see picture below). Eventually you will develop an ear for this and will line up songs without even looking at the software.
Keep experimenting with different songs and different methods. Once you can get two songs playing in-sync, try mashing up different parts of both songs. It often works well to mix the instrumental version of one song with the vocals of another. If things aren't working at first, don't get discouraged. The key is to keep trying new things and always have fun!