Advice Needed

I was just offered a gig to do some outside family portraits for my sisters friend.
She asked me what I charge, And I really don't have a clue what to charge
What do you guys usually charge for this kind of thing?

I have taken some nice portraits lately, and she has seen them and was really impressed.
To be honest I am pretty nervous about doing the shoot especially if I am getting paid for it.

A few questions I ask are

1. Best time of day to do the shoot?
2. which lens to use 28-135IS . 18-55 kit lens or Sigma 70-300

last few times I took some portraits i was having some focusing issues so I hope I can correct the problem

Thanks in advance

outside family portraits, how many people? 1,2,3, 400?

What I'd do is shoot early in the morning or late in the evening. Don't shoot at noon or something like that, the sun's light won't be very flattering.

I'd use your 28-135 Is lens, as it seems to be the most versatile lens for this kind of shot.

forgot to add there is 3 people including a 1.5 yr old boy

You may want to charge a sitting fee of anywhere from $75 to $150 for your time and talent. Then post the images on a gallery for them to order prints.