Like pickpocketing and sneaking when there's enemies nearby.

There are perks that specialize in both of those areas that will make them the most efficient. The Pickpocket perk is the first Perception perk and requires only one point, meaning, you don't need to invest in Perception to get it. The Sneak perk is an Agility perk that requires 3 Agility. Both improve what their name implies.

Honestly, I assume you've played the game to some extent, surely you've looked at the perk chart yourself and noticed these perks exist.

To be fair even with agility 10 and sneak maxed out it is rather spotty at actually allowing you to be stealthed, and that is including stealth gear/mods. Also depends on your difficulty though. I still find very hard a lot harder then survival.

Your chances of remaining undetected are affected by more than just your agility, sneak perks, and stealth mods on your armor.

Lighting has an effect.

The weight you are carrying has an effect.

Perception of what you are trying to sneak up on or sneak past has an effect (some creatures are more perceptive than others).

The field of view of what you are trying to remain hidden from is important, Basically, sneaking up on a raider from behind is a lot more effective that trying to sneak up on him/her from the front.

Stealth Boys and Stealth fields only cancel the effects of ambient light. That is to say, At high noon, in the middle of a floodlit courtyard, a stealth field will be of significant value. At at midnight, at the bottom of a coal mine with heavy cloud cover and a lunar eclipse a stealth boy is useless.

This is very very helpful. Thank you

It should also be noted that it is unusual to be 100% undetectable. In most cases there is a chance you will be discovered.

{Edit}

I also forgot to mention that moving is a factor. You are less likely to be detected if you are stationary than you are when moving. Also, until you get the Sneak 4 perk, movement speed is a factor., Slower is better. Once you get Sneak 4, movement SPEED doesn't matter.

well you can severely minimize this chance through gear and gathering the sneak books/bobblehead. Also in my melee stealth playthrough I had the serendipity to have 4 pieces of armor with the chameleon affix on them. It got to a point where I could crouch right near an enemy and swack them with my sword, even if it didn't kill them outright they would go into the "caution" mode trying to find me, even though I was right there.

Yep, you can get to the point where you are almost a ghost.