The first stage of almost any trip is planning stage. You should plan everything about where you are going to get and you should plan all resources that you might need in your journey.
As for resources, typically you will need the same "resources" in any kind of travel, e.g. some clothes, good footwear, some medicine, money, documents and so on. It sounds like a time-consuming task to get all these things into one place and don't forget anything, but there is a secret, which unveil how to get all things ready in just 30 minutes. The ideas is to create a check list of things that you usually should take with you, for the first time this list will not be complete, but once you have traveled two or more times, you will have your own personal travel check-list.
The best advice would be - it is possible to buy anything that you might forget, so make sure you have not forgotten money, your travel passport and health insurance. Make sure you are prepared to various weather conditions, and for sure, it is a good idea to check weather report before you start you journey.
The second stage of planning trip is planning your future route, e.g. places that you want to visit. The idea is to spend not much time on this task, but get good results when you will be in place. If you already have a good printed map of the city that you are going to visit, then it would be possible to create a route, plan everything at home. If you don't have such a map - it is not a problem, when you will arrive you should find the tourist office, where you will have a map of the city. Usually these maps already contain necessary information about top places to visit, but only about places located in the city.
Good idea about planning trip is to find and print out information about places that you wish to visit and that you find interesting. When searching for this information, make sure you have not just the name and description, but preferably the address of the point of interest and some information about transportation. If you are using a public transport, then it is important to know what stops you will need and what line numbers you need to take and in what direction.
Make sure you know about opening hours. For instance, some places (like gardens) are not opened in winter. Most museum don't work on Monday, and most shops are closed on Sunday. If you are interested in churches, then have in mind that you will be able to access most religious places on Sunday only after 13-00.
General recommendations about planning trip are: get all things you need and create a checklist for future trips, get information about places of interest and make sure you know their opening hours. Plan your trip accordingly and don't forget to get some time for rest and food.