Overcrowding the garden

Hi group.  NJ zone 6 here.  For the past several years I have gotten greedy
and end up planting my plants way too close together.  The peppers in
particular don't like this, end up tall with small peppers if any.  The
tomato patch was so crowded they could not get picked and spoiled.

This year I have vowed to reform.  Now, how crowded is safe?  I don't have
a
lot to work with.  I have two 10 by 12 plots seperated by a 3 ft wooden
walkway.

I plan to dedicate one entire side to tomatoes.  How many and what
configuration would you suggest?  Any ideas for the peppers on the other
plot plus other stuff like squash, peas, greens?

Thanks for your ideas.