-use real object or situation that match their cognitive level to demonstrate. Make it fun!
-give out the script and let them read as motivation.
-ask them to take part in the role play (they can hold the paper) and you have to play the role of Joe as you are the main demonstrater. Smile!
********************************
e.g. Role play
(Joe and Mark are good friends. Joe brings one of his gfs, Liza to have a drink with Mark. )
Joe: Hi, this is my girl friend, Liza.
Mark: Joe's girlfriend! Hi, Liza!
Liza: Hi Mark! You must be Joe's best friend.
Mark: you may say so.
(Joe's another girlfriend, Jane, comes in and Joe approaches her instead of letting her join the table)
Joe: Hi, Jane!
Jane: Who is she, Joe?
Joe: This is Mark's girlfriend.
Jane: Mark's gf!
Joe: Yes! They are talking about their wedding plan. Sorry, I gotta go. Call you later tongiht!
(Then another girl comes in and repeat the scene several times.)
************************
- Take other object to demo.
- basic knowledge about possessives (you tell them the pattern or you may ask them to derive the pattern from the example of the script)
-Learning Sheet: circle the best answer:
they have the choices or (Mark / Mark's)etc to choose from in a cloze passge to make sure they know how to use possessives. (Mark has to be right in some questions; otherwise they just see " ___' s" and circle them)

Well....take a cultural object...or just every day objects (this way they are learning ideas and/or vocabulary at the same time) pass the object around the class saying "my scissors, your scissors, etc" well..maybe it is cheesy for adults....but when you are using actions it will help stick

I know this is a little opposite but you may be able to flip it your direction.... When I was in Spanish class we learned all of our conjugation with a grid. The different types of people would go down the left column: I, he/she, they, we, you all
And the verb or whatever word we were conjugating would go on the right. In this example the verb (to be) like is
Yo / soy
El / es
Ellos / son
Nosotros / somos
Ustedes / son

if there were more tenses like past tense it would go the same way in a new column on the right:

Yo / soy / (past tense conj here)
El / es / (past tense conj here)
Ellos / son / (past tense conj here)
Nosotros / somos / (past tense conj here)
Ustedes / son / (past tense conj here)

So to teach English it would probably go...

Subj -Pres. -Past.
I - am - was
He - is -was
they-are-were
we-are-were
you all-are-were

I dunno why, but it worked in Spanish class pretty well, then all we had to do was memorize the irregulars and we were good to go.

After learning a bit, other-language immersion also works wonders too. It's like it flips a switch in your head and then the next thing you know you're babbling on a mile a minute when you didn't know you knew so much of that language.