3-bet sizing

[Hattifnatt]

I post this in SSNL instead of MSNL because I think its more appropirate here.

In general, when you 3-bet preflop, how much do you 3-bet?

What factors do you take into account and how does that affect the size?

Ex of factors: Your hand, How deep the stacks are, Type of opponent, Your image, History.

In general, I 3-bet to like 3*the original total raise and add some most of the time. I tend to add more if OOP than in position. If there is cold callers inbetween I add about the sum of the cold call as well.

Can you give examples of when you tend to 3-bet more or less than usual?