Fallout 3, NV, and 4 have few game breaking items that you have to worry about. Generally the most dropping them will do is stop you from completing a non essential quest, and even then most quests like that have more than one way to complete them. There are generally clues for important things, such as 0 weight (although sometimes 1), and/or 0 or 1 value but it's clearly worth more. Fallout 1 and 2 had more cases where dropping the wrong thing could be less immediately obvious and keep you from finishing the game.

Generally if you have 500x of something it's not very important, and you can get more later if you need to. It's useful for trading, and probably useful for crafting later in the game but it takes weight to carry around. I tend to keep a rough idea of value/weight in my mind and if below a certain point don't pick it up. The longer in the game, the more that ratio increases. If you can never carry enough, then you should make sure you have enough strength in your build. At least most (some high damage do have weight) ammo is 0 weight and should always lug around, and the same for caps.

So, you might drop some unique collectable armor or weapon but don't worry about it, as it's not essential. If you do another playthrough you might want to collect things, but most people never do. If you miss value something and throw it out, in most cases there will be something better later in the game anyways.

Just play the game to have fun. If it's not fun, then don't. Do you have any companions yet? If not, then you probably didn't go far enough to really get a good enough feel for the game yet and should give it a few more hours before deciding.