kama - to come, to happen, to cause           
kiwen - stone, rock; hard like a rock
kon - air, spirit, wind, atmosphere

pana - to give, to send, to release, to emit

kepeken - with, using, to use;

lon - in, at, on; to be in/at/on/to, to exist;

tawa -  to, for; to go to, to move;

poki - box,container, bowl, glass, cup, ,etc....
toki -  language; to talk, to speak
lape - sleep

pini stop, end

The use of lon , tawa & kepeken

lon, like tawa and kepeken, can be used as both a verb and a preposition :

Kepeken as a verb:
mi kepeken e ilo. - I'm using tools.
sina wile kepeken e ilo. - You have to use tools.
mi kepeken e poki ni. - I'm using that cup.

Kepeken as a preposition:
mi moku kepeken ilo moku. - I eat using a fork/spoon/any eating utensil.
mi lukin kepeken ilo suno. - I look using a flashlight. (ilo suno = a tool of light)
Note
lon ni means here or there

The use of lon

mi lon tomo -- I'm in the house....(lon is used as the verb)
mi moku lon tomo -- I eat in the house...(lon is used as a preposition)

Since lon can be used as either a preposition or a verb, the meaning of the sentence can be a bit confusing when used with wile.
  
mi wile lon tomo  this sentence has two possible translations:
I want to be at home (the speaker wishes he were at home)
I want in the house (the speaker wants to do something in a house)

Toki Pona often uses  e ni to split this kind of sentences up to avoid confusion:
mi wile e ni: mi lon tomo --> I want this: I'm at home.

Pay attention , lon, doesn't have an e after it.

suno li lon sewi -- The sun is in the sky.
mi telo e mi lon tomo telo. -- I bathe myself in the restroom.
kili li lon poki. -- The fruit is in the basket.
mi pini e lape sina. -- I ended your sleep. I woke you up.

The use of tawa

Using tawa as a verb.
tawa is similar to lon, tawa doesn't have an e after it.

mi tawa tomo mi -- I'm going to my house.
ona mute li tawa utala - They're going to the war.
sina wile tawa telo suli -- You want to go to the ocean.
ona li tawa sewi kiwen -- She's going up the rock.

Using tawa to mean to

tawa is often used as a preposition.

mi toki tawa sina - I talk to you. (literally)
ona li lawa e jan tawa ma pona - He led people to the good land.
ona li kama tawa ma mi - He's coming to my country.

ni li pona tawa mi - That is good to me. (or, in other words, I like that.)

And to say that you don't like something, replace pona with ike

ni li ike tawa mi - That is bad to me. I don't like that.

Here are some examples:
   kili li pona tawa mi. - I like fruit.
   toki li pona tawa mi. - I like talking. or I like languages.
   tomo li ike tawa mi. - I don't like buildings.
   telo suli li ike tawa mi. - I don't like the ocean.

Keep in mind that e can only come after the verb of the sentence.

mi lukin e ma. ni li pona tawa mi. - I'm watching the countryside. This is good to me.
ma li pona lukin. - The countryside is good visually. The countryside is good to look at.

Using tawa to mean for

Okay, so tawa essentially means to go to or simply to, but it can also mean for, as in this sentence:
mi pona e tomo tawa jan pakala. -- I fixed the house for the disabled man.
Unfortunately, the trick of letting tawa mean both to and for isn't without its drawbacks. Keep reading to see why.

Using tawa as an adjective
   tomo tawa - car
   tomo tawa telo - boat, ship
   tomo tawa kon - airplane, helicopter

tawa as an action verb
   mi tawa e kiwen. -- I'm moving the rock.
   ona li tawa e len mi. -- She moved my clothes.
tawa can be used as an action verb in these situations because there is an object.