Any tips on travelling from Belem to Manaus and on to Porto Velho by river please?

Looking at making this trip in September only have a few weeks to complete the trip and would like to get as much from this as possible. Any hints or Do's and Don't's would be appreciated.
Any tips on travelling from Belem to Manaus and on to Porto Velho by river please?
Wow, that is a trip even many Brazilians would be wary of.Take yellow fever vaccination, bring malaria tablets and bring loads of insect repellent for starters. Since you are travelling by river the best is to rely on locals, making sure they have the permits (there have been incidents of illegal overcrowded ferries sinking).

Here is the National Tourism agency website:
http://www.braziltour.com/site/gb/cidades/materia.php?id_cidade=7410
Any tips on travelling from Belem to Manaus and on to Porto Velho by river please?
Do stay in the porto velho, don't drift out to sea. You'll end up bobbing on the ocean. Sharks.
Do stay in the porto velho, don't drift out to sea. You'll end up bobbing on the ocean. Sharks.
I discourage you to swim it all the way, I'd use a boat of some sort
Go down to the port and ask when the next boat to Manaus is leaving. You might have to wait a day or two. My boat was working with only one motor when I made the trip so it took 7 days instead of 5 and often had to travel on the side of the river where the current was less strong (it RAINED bugs in the evening). Bring a hammock with you to string up with everyone else! It was one of the most memorable experiences of my life! I loved it. Bring some food too (esp fruit, on my boat same predictable orange food every day- spaghetti, rice, feijao) and a pack of cards or something. Boa viajem ;)
ttomnl gave some good advice. You may also want to look at the archives of a similar discussion on the BrazilMax Forums. See the link below.