@MirekE has some great advice. I would also add that you can play around with over and under developing easily with your 35mm. Find a scene that shows a wide range of values, ideally a scene where you can set the lens to infinity. The sun should be behind you and over your right or left shoulder. No clouds if possible so the lighting doesn't change suddenly. Point the camera at the scene and shoot every frame at the same ISO, aperture, and shutter speed. Using a tripod is nice so there are no changes in framing.
Did you just throw away a roll or film? No way! Now it's time to develop. Pull 1/3 the length of film out of the canister and cut off. You'll do this in the dark of course so having a yard stick marked with something like tape (that you can feel in the dark) will be useful for measuring out the correct amount of film. Develop a section normally (we'll say the time prescribed by the manufacturer), develop a section normal-1 and develop a section normal+1. +1 means overdevelop by one zone, -1 underdevelop by a zone. To figure out exactly what these should be would require more tech and experimentation but you can often change your development time by around 1/3 in either direction to get a sense of the change it will give you; more contrast and less contrast. You may find that you like the results better than developing "normal".
Note that if you doing this with T-Grain films like Delta 100/400, the overdevelopment/underdevelopment times should be much shorter as those films are more sensitive to time changes in development.
Also, a good starting place for information regarding development times with a given developer/film is The Massive Dev Chart