Do you need help keeping a steady tempo? Have no idea what is meant by Adagio? Do complicated meters terrify you? Let me introduce you to the metronome.
My personal favorite kind of metronome is the very classical mechanical metronome. Its pendulum gently sways side to side, and you hear a click clock that marks the beat. These are not very portable, and only offer a steady beat and pulse interpretations of tempo markings. They look gorgeous on your piano, though.
The kind I recommend is the battery operated metronome, like this one by Wittner.
In addition to being highly portable and inexpensive at around $20, this metronome comes with headphones so only you can hear the pulses, or you can disable noise completely in favor of a pulsing red light. Also, it has a dial that play A440 to help you tune.
The last kind of metronome is on your smartphone. There are hundreds of apps for metronomes, but I like Metronome Pro (which is not free but under $10). In addition to everything the above metronome has to offer, this app allows you to assign different sounds to different beats in the measure (clock for the downbeat, then click, click, click for the other beats in 4/4 time, for example). This is a life-saver in non-standard metered pieces.
Personally, I like physical things so the mid-priced Wittner metronome gets my vote, followed fast by the app. Hope this helps you stay rhythmic!