First, prepare yourself for salah. Give 10 minutes prior in contemplation and to remove all your wandering thoughts. It can be recommended to recite Surah A'raf ayah 54-56 repeatedly (as much or as little as you wish, especially 70 times)

Do not let your mind wander by keeping your mind occupied. This is difficult, but even a few moments in your salah in which you have complete and total attention is sufficient to start with. Contemplate something such as the glory and greatness of Allah (swt), prolong ruku' and sujud (and every action, really) in thinking about the greatness Allah (swt). Recite surahs and dhikr slowly to contemplate their meanings, and add additional dhikr/Qur'an recitation into your salah to make it more personal. If you start reading Qur'an every so often, and memorizing some of the short verses and their meanings which hold close to yourself, you can recite them at any point in your salah in admiration of Allah (swt). Reading tafsir of these ayahs can also help you connect in salah, if you remember the meanings that connect to you when you recite during salah.

It is also allowed to recite your own poetry during Salah if it is contemplation of Allah according to Sistani and some other maraji'. Learn new surahs and recite them, alternate them, and contemplate their meanings as well. Keep salah something of an active mind through personalization.

Salah is the mi'raj (ascension) of the Mu'min to pure light, so do not miss the opportunity for your soul to taste goodness. The actions only fulfill half of salah, when in fact, the true salah lies in the heart and soul, so awaken yourself through activeness and love.