Play the tactics trainer each day; it's fun and it doesn't take a lot of time.
When you are starting out, the most important things are king safety and not hanging pieces. Next is tactics, and if you master those then move on to deeper strategy / positional awareness and evaluation.
Repetition is key also. A grandmaster has memorized tens of thousands of positions, maybe even more, and relies as much on this memory as he does on calculation. Without this lexicon of experience a player can't advance to the top level.
Chess is very hard and most people don't make master no matter how hard they try, but if you enjoy the game and make progress that is what really matters.
OR
just plain, enjoy chess put in a moderate amount of time and effort at it Play in a club and attend tournaments as your able to (expense and difficulty) keep doing this for months to yearsand see how far you can get.
25 might be too old to hope for Gm, but its a better time in life to improve, than for example, 42.
Hey now, watch it kid! I'm only 5 months and a day away from 42 myself!