There are so many websites that are available out there that offer up a wealth of information on what you need to know when you are planning a trip to trek Machu Picchu. The most important thing to know is that in Peru, the seasons are not necessarily the same as what you are experiencing at home. This is important to note, because packing for the wrong weather or climate can effectively ruin an otherwise well planned trip. There is certainly a rainy season in Peru, and that means that you would need to ensure you are prepared for the rain to be a constant part of your travels and your trip. This is why you really should become very acquainted with the weather and the forecast for the part of the country you are traveling to, and what time of day you will be outside doing your activities. It is necessary to pack for the current climate, even if it is opposite what you are experiencing at home. This is the most important piece of advice that I give to those who are starting to plan a trip where they will be doing trekking of Machu Picchu. The wrong clothing for your trip can effectively ruin your best laid plans.
The second piece of advice that I always give to travelers who are planning to do the trek or the hike is that they need to prepare in advance for the physical toll that the hike is going to take on your body. If you never go for hikes, if you do not ever experience elevation in your life, and if you are not in decent shape, the trek may be a bit much for you. You do not want to waste your money by planning for and paying for a trip up the mountain via trek, and then arrive to discover that you physically cannot complete the journey. Often, the trek leaders are not going to give you your money or your payment back. And you will be left taking the train to the top of the mountain to see it rather than trekking Machu Picchu. This would be a discouragement for anyone involved, so I always advise travelers that they need to be prepared for the high level of physical strain that it will take to get to the top via a hike.
Look into your other options, because you can take a bus or you can take a train. The bus gets your close enough to walk in one day to the top, and the train will take you all the way to the top. This is the best option for those who are not able to do the trek. Other than that, just be sure that you are prepared for food that is different than your own, and a possibly different standard of accommodation for your stay in a hotel in town. The air conditioning and the food are not always at the same level as they may be at in your country.