Along the lines of what @Xann009 said, a classic technique is to develop the habit of doing dream checks through the day. Since there are certain anomalies that characterize dreams (e.g. mechanical and electrical devices don’t work as expected, printed text is unreadable, etc.), you can cultivate the habit of, say, routinely looking at clocks to see if they’re behaving, or flipping a light switch to see if it does what it’s supposed to, or reading some handy print, even when you’re sure your not dreaming.
The idea is that this habit will carry over into your dream life and you’ll occasionally be surprised to find that one of the tests turns out “positive”. So basically, your training yourself to continually ask, “Is this a dream?”