what are the key things the person should know for equal business partnership ?

partnership is not always good thing
but some times it helps to efford bigger economic project.

for example , i go to business partnership with some one
to have 50/50 partnership with new hostel.
is it necessary to involve the lawyer or we can make agreement just between ourselves without lawyers help ?

we plan to be equal with every thing
both have money and enthusiasm

In the societies where economics is legalized - every thing is simple
but in a more primitive , corrupted societies where authorities do not want to legalize economics it is difficult to prove some thing stricly according to the laws.

for example - there is no hostels legislation... clanish hostels association with an appetite of monoplolizing the industry ....and so on

also , there are some times dis honest partners...or lazy ..

so , what are the basic things one should know before he goes for hostels business partnership , no matter in what country ?

does any one can say from experiense ?