It can be complicated if you don't know how to deal with the locals, They'll come up with the most incredible excuses to get money from you and if you actually do it they just won't stop, specially if you happen to have any problem with a land owner, they'll ask for 'compensations', that's the word they use, and if you pay, eventually more 'land owners' will appear asking for the same or more.
People on the coast are very friendly, but as you go west, they can get more a and more hostile. I wouldn't advice to go alone specially if you are not used to deal with these kind of situations. If you are an experienced traveler, just do aso you always did, be respectful.
Since Papua New Guinea is called 'The Land of the unexpeccted' I think is wise to go there 'expecting everything', because believe me, anything can happen there; that way you will always be one step ahead and won't let them take advantage of you. almost 4 years ago
I realise this is over 3 years old but for anyone thinking of doing West Papua solo I would check out the current situation with the Free West Papua movement.
I was in West Papua a few months ago and without a well established and checked prior to arriving local contact with transport and able to help you I would consider twice.
There are villages in West Papua that the locals do not want visited by anyone much less wandering tourists. Amazing place though! about 2 years ago