I've seen Luc say before that he just tries to fit in with an average buy for those smaller volume type coins. With many of the smaller coins you just don't want to stand out and you should be fine. If the coin itself has a volume of 50 bitcoins a day then yea putting 10 in as a buy could be a risky proposition. Putting 1/4 of a bitcoin would probably be just fine, but again it all really depends on the coin, the point to be taken is with the lower volume coins to just blend in with the other average buyers.