Your gear will work just fine for portraits, provided you have good light and use the
correct focal length for the subject size. You can use either camera, except if you want
to take a head and shoulders shot, for which you;ll need the 210 mm focal length.
The advice for your situation is not the same as the advice for a professional studio.
Light choices, best to wrost:
1. Outside: thin overcast.
2. Outside: in bright shade
3. Inside: large north-facing window
4. Inside: any large window
5. Inside: many bright room lights with shades.
6. Bounced flash
7. Off-camera flash
8. On-camera flash
Avoid harsh, glaring light. Soft and bright is what you want.
On a dim, stormy day, you will need to drag a few extra floor lamps
or table lamps into the living room, and put them together near
one wall.
Position your subject with the light coming over your shoulder
and falling on the sitter's face..
Look over your sitter, and ask him to remove any hat or anything
unsightly (e.g, sticking out of a pocket).
The darker the shadows (more contrast) the more "dramatic"
the portrait. If the shadows are too dark, use a reflector -- anything
large and white--to fill them in.
Set your camera to Aperture Priority mode, and select the largest aperture.
If you own a monopod, now is the time to use it. If not, hold the camera
as steady as you can (especially for any long focal length shots).
Stand 15 feet away from your subject (
important!).
Zoom to however much of the subject you want: full standing figure
50-70 mm), full sitting figure (70-105 mm) or head and shoulders (210 mm).
Change lenses if you need to, but do not move closer to the subject.
Shoot many diffrent poses and angles. Try different backgrounds
and different lighting. Try to make it fun and interesting for the sitter.
Then carefully review your photos in the camera, and decide if they
are what you wanted. Magnify a part of the image that has detail
to make sure that it's in focus. If you are happy with an image, that's
all that matters.
There are other good ways to take portraits, but all involve more
equipment and/or carry more risk of failure.
If you used room lights indoors, the color will be too reddish, but
you can fix that easily with processing software. Avoid excessive
processsing.
It's a good idea to practice ahead of time on convenient family members--
as photographers have always done.
Your gear will work just fine for portraits, provi... (