Q: Can you give me a list of important baking tools so that when I start my own baking set I would not end up buying anything unnecessary?

A: First thing you have to do is to decide which  desserts you will bake more often. Will you be making cakes, bars and brownies, quick breads, cookies or pies?  Your choice of desserts will dictate the baking utensils you have to prioritize in buying. 

Do remember one thing: keep utensils for making desserts solely for that purpose.  Using them for cooking savory items might leave odors / stains that might affect the taste / flavor of your baked dessert items. 

Basic Needs:
Oven
Oven thermometer
Durable and thick kitchen mitt / potholder
Liquid measuring cups (preferable glass)
Dry measuring cups (pref stainless)
Measuring spoons (pref stainless)
Rubber spatula (different sizes)
Mixing bowls, pref stainless (different sizes)
Sifter / strainer
Wire whisk
Hand mixer or stand up mixer
Kitchen knife (solely for baking)
Chopping board (solely for baking)
Wooden spoon (solely for baking)
Foil and plastic wraps

Extras:
Timer
Blender / food processor

For cookies:
Small ice cream scoop for cookies
Cookie sheets (that will fit oven)

For pies:
Pie pans (8” and / or 9”)
Pastry brush
Rolling pin

For quick breads, bars, and cakes:
Baking pans (rectangular, square, and round, loaf pan)
Piping bags and tips
Cake tester
Metal flat and offset spatula (for icings)
Muffin pan