Consider your reasons and make sure you really want it, suicide is a permanent solution but once you make it you cannot go back. If done improperly it can also just damage you physically and make life worse.
Whether you leave a note is up to you. Wikipedia lists common reasons for leaving a note as to dissipate guilt, increase guilt, declare a reason, send a message to the world, express thoughts you couldn't in life, give instructions for disposal of your remains, or confess to an offence. If anything like this is something you would like to do, you should maybe consider it. Also keep in mind a "note" can come in many different forms. For me, whenever I've written them they always seem to balloon to be multiple pages long and discuss reasons why, thoughts I have for the living, and how to take care of my cat. For some people though, it could even just come in the form of a single text. Maybe just messaging "I love you" to someone close could also qualify as a note. I think in a lot of ways suicide is about control, so if you leave a note it's in your control and do what you want.
I think a will/finances will vary greatly depending on your situation. I don't own much beyond my cat, some savings and a car. Usually people with a large "estate" have an actual will, but not sure what the logistics of this would be in suicide. If you're a younger person and you're all of a sudden trying to write a will and get an attorney it might arouse suspicion. My circumstance is that I mainly just care about my cat and I want someone to take care of him - namely my brother or dad. I don't think this would legally be an issue, I don't see why the government or anyone else would contest my brother taking care of my cat. My car and savings I don't really care about that much, so I assume they will just automatically go to my next of kin (my parents). At least where I live next of kin is usually your spouse, if you don't have a spouse then it would be your kids, and if you don't have kids/a spouse then it would be your parents or other relatives (siblings, cousins, etc). I imagine most people are ok with your belongings being distributed in this way. If you have specific wishes, a note that contains wishes for what happens to your belongings probably isn't 100% legally binding, but I don't see why relatives wouldn't uphold it in most situations - again unless you're not on good terms. I also feel like if it's "small" things I doubt the government would get involved. I don't think they care if your guitar goes to your uncle or your computer goes to your brother. I think those types of issues mostly arise when people own millions of dollars of property or are sitting on substantial investments or something.
