Ignoramus24949 wrote:
i have some bald spots in grass. What is the proper procedure to
re-seed them.

They appeared due to two causes, either one of another:

1. too much walking

You need to break up the soil. Core aerators are preferred but
expensive. A spike aerator or in a pinch a garden fork or rake could be
used. Get some air and water in there, fertilize, seed, water, hope.

Meanwhile, reroute the walking. (Or reason that it isn't possible and
put in some flagstone or something.) If you really can't, consider an
"overtime" seed mix that will give you a tougher, wider-blade grass
similar to what you might find on an athletic field.

There are lawn "patch" kits you can get that include seed, fertilizer
and peat moss to help but I've had only partial success with this method.

In any case as long as you moderate your expectations -- you may see 50%
improvement in coverage of the bald spot, for instance -- you should be
able to do OK.

2. Some areas are shady and somewhat arid due to a hill.

Any ideas on how I can get a good grass going. Should I rent a power
rake, any fertiliser to buy, etc?

Scotts has a four-step system which is probably a basic first step here.
(You can often get a generic alternative for a little less, e.g. at
Ace.) Basically spring, early summer, late summer, and fall, they're
different fertilizers for different growth seasons. Just try to go
through a full year doing all the right things on schedule and see if
that comes through for you -- because trying to fix a broken lawn can be
a lot of work that doesn't go anywhere. So try the easy route first.

For the shady areas, overseed with a shade-happy grass mix. Over a
couple of years that should improve things.