I’d recommend the interlinear Tehillim, because then you can learn what the Hebrew means word-for-word. Even if you can’t read Hebrew letters yet, you’ll learn soon enough with some practice. You can see samples of it on the Artscroll website.
It’s a good and time-honored practice to recite Tehillim in the merit of a sick or deceased person (or in wartime for the safety of Israel), in the hope of inspiring Hashem’s mercy. But it’s also good to recite Tehillim more regularly as a way of getting closer to Hashem. Here’s a part of quote I like on this topic:
“When reciting Psalms and prayers, make sure you find yourself in everything you say. It is simple and easy to find yourself in all your prayers: you don’t need to be clever.
The Psalms in particular were written for the entire community of Israel and for each and every individual. All of a person’s internal wars and struggles and everything else he endures are all expressed in the Psalms , which mainly relate to the war against the evil urge and its forces. These are the main enemies seeking to keep a person from the path of life and drag him down to the deepest hell if he is not on guard against them. The entire Book of Psalms is about this war.
The foundation of all the different pathways to God lies in reciting Psalms and other supplications and offering our own personal prayers from the heart, entreating Him to draw us closer to His service. This is the only way to win the war. Happy is the man who persistently prays and entreats God at all times and in all situations, because he will certainly win the war.”
Likutey Moharan II, 101