How to make a proper guess at a particular solution

]My question is how do you from a proper guess at the particuliar solution of a differential equation for example.

Say this is the right hand of the equation

$\displaystyle

sin(2t)+te^t+4

$

I know it helps to break it up into seperate parts, but I am working with a book solution here and my guess are just off it seems from the books proper guess.

My guess for

$\displaystyle sin(2t)$

$\displaystyle

Acos(2t)+Bsin(2t)

$

Book's guess

$\displaystyle

t(Acos(2t)+Bsin(2t)

$

and the for the term of 4 the book's guess was

$\displaystyle

Dt^2$

How do you properly determine a guess like this?