When I went to Peru in 2001, I could get my residential visa by simply entering the country as a tourist and doing the necessary paperwork. In 2005 I wanted to do repeat that process, but the Peruvian consulate in Amsterdam apparently thought it was not important to tell me that at that time you had to start the procedure from the country you were residing. I had to spend too much $$ to correct that problem. Nowadays, every time I'm going through some kind of procedure, I ask, ask and re-ask (does that verb exists?): "Is this everything? Am I done? I don't need to do more paperwork? I don't need to make extra payments?" Additionally, I try to find confirmation in other places, and even after being so meticulous, I still face surprises now and then.
Bottom line is: Better ask too much than too little! Especially when the following phrases/questions/thoughts pop in your head whilst visiting places such as RENIEC, DIGEMIN, etc:
"Naah, this is so illogical! It can't be true!" (=Better believe it, it's real!)
"I think this is all." (= No it's not. You need to make payments. Fill in extra forms. Seal missing,etc.)
"There is no need to....." (= For them there is)
"Why do they need this?" (=Extra documents to add to their stockpiles of paperwork in order to justify their long waiting times due to their sheer incompetence)
"In my country...." (= We're not in Kansas no'mo Toto!)
"I know I'm ready, because I did this procedure before." (= Yes, and yesterday they changed the rules)
"Last time I had to pay 25 soles, I'll take 40 with me (= Silently they raised the price to 38 and your parking costs 2 soles per hour. Time's ticking mate!)
I could go on and on. Actually, I've always had this idea to publish a book with real time stories and infamous quotes about Peruvian bureaucracy!