The Triangle is a universal type of reading with a very clear and evident structure. It casts light upon the three elementary dimensions of past, present, and future. It follows the wisdom of the Nordic Norns and the Roman Parcae. Choose your question with care - the more precise the approach, the more helpful the answer.
This is one of the most classical tarot spreads, asking for past, present and future. This reading is universally useful and it follows - like most relevant matters in our lifes - the flow of time, with roots in the certain and immutable past, a strong relation with the present which is shaping everything, and an outlook into the uncertain future. Within this logic, you can address any topic big or small with the triangle spread.
Please be aware of the fact - especially as you are interpreting the card representing the future - that the tarot is not a horoscope, and that it does not produce definitive prophecies. If you draw cards which are very promising at a first glance (like "Love" or "Harvest") or negative (think of "Defeat" or "Torment") it does not mean that fate has already decided about your success or defeat. It simply means that you should consider the quality of the card you have drawn, especially in regard to your intentions and your initial question.
Use the tarot as an inspiration, but do not blindly follow an interpretation which is and will remain always a subjective view only. The tarot does not change your responsibility for your actions. Of course, if you consult the tarot with care it does help you assessing your situation and it does provide you with a frame for your thoughts, which indeed is the significant inherant value of the tarot, the oracle of what is possible.