Hi starz, and welcome to Aeclectic!
Many readers here will tell you that one single card can become over an hour's worth of discussion with a querent, because it each Tarot card there is such depth, and it often brings out things in the querent's mind that they wish to discuss. Sometimes, one card does the opposite: it gives you a simple, one-sentence, clear answer quickly. I often use just one card for 'Yes/No' questions or questions such as 'What will happen tonight?' Basically, anything that is a simple question.
However, for the more complex questions (spiritual path; love and relationships; conflicts; anything the querent feels is complex; anything with stuff behind it and causing it; etc) choosing a spread can be a lot more difficult. It can help to have a few well-loved spreads as a stand by that you use often - what these are depends on you. My personal stand-by is one that I use when the querent has a choice to make: I lay x-number of cards (this depends on the question) on one side, and x-number of cards on the other side, and read each side as though they were the different options. This spread is slightly changed to fit the exact question, number of options, etc, but it is useful to bring out. The Past, Present, Future is also a handy spread that you can espand upon more to fit the querent's question. For instance 'Past' could indicate 'Causes of the situation' as well as the general atmosphere of the past, or how the querent felt in the past. 'Present' could include cards for the querent's feelings at this time, influences surronding them, the situation itself, etc. And 'Future' could include advisory cards as well as 'what will happen'.
What I am mostly suggesting is that whilst you may want a few 'stand-by' spreads under your sleeve, these spreads should be such that you can expand them or change them to fit the querent's question. You could identify the main parts of the querent's question, and lay out some cards for each part for instance - you don't even have to lay them out in a shape (I only do so if I have limited table space.)
So, to sum up a long post - I would suggest deciding on a spread by looking at the querent's question and what they want to know (because the two can be very different things, or the first does not completely elucidate the second). Fitting a spread to the question tailors the reading more to the querent, instead of trying to fit the question into a spread that may not be useful for it.
I hope this helps!
Blessings,
Kiama
