I am having trouble not doing things that I am unsure about whether or not they are sinful, such as drinking soda, eating sweets, masturbation, and whether or not I should be playing certain card and video games. On the soda and sweets, I am wondering if I am harming my body by doing so, and on the games, my worries range from should I be playing them at all to details such as whether or not the length of my character's hair matters or not. Oftentimes I authorize an action then once it is done think to myself that I shouldn't do that. I think that I often have trouble viewing doing something that I am not sure about as sin.
Do you have any insight on the topics I mentioned? And what should I do about the things that I am unsure of?
Also, I just want to thank you for being there to answer questions that people have.
You are falling into what used to be scrupulosity. It is the old word for being OCD about religion. You found out that many things you never thought about before can be wrong and then you go to the other extreme and find faults under every rock. See Extremes.
What you are missing is that some things are wrong, not in themselves, but because of when they are done, how they are done, or how much they are done.
For example, sweets are not bad in small quantities. "My son, eat honey because it is good, And the honeycomb which is sweet to your taste" (Proverbs 24:13). But when over-consumed, problems arise. "It is not good to eat much honey; so to seek one's own glory is not glory" (Proverbs 25:27). Entertainment is the same way. Recreation is good for a person. All play and no work is bad for a person.
Sometimes when something is done makes a difference. "A time to weep, And a time to laugh; A time to mourn, And a time to dance" (Ecclesiastes 3:4). Fooling around with friends at a funeral would be bad timing. Deciding to bathe in a public park is the wrong place.
Sex is expected in marriage but becomes wrong before you are married (Hebrews 13:4). It is the same action and could be with the same person, but circumstances make a huge difference. Masturbating is not wrong in itself, but when you masturbate while looking at pornography or masturbate with some other person, then it becomes wrong.
Some things are wrong because of what they involve. A video game that features nudity or murder as a form of entertainment would be wrong because they are promoting immoral ideas. In the same way, dances that emphasis sensuality or sexual movements would be wrong because it stirs up lust.
Paul's comment about the length of hair means there should be a distinction between the sexes. The number of inches long your hair is given on purpose because people would focus on that and not the bigger issue. The real question is if someone just saw your hair, would they know you are male or female?