In a perfect world, I would wait until everyone had played a few games before wagering, because then I would have more info to use in capping. Unfortunately, this also means the books have more info in setting the lines. I do a lot of reading about teams over the offseason and comparing matchups and the like, and then hope that the early season lines are based more on public perceptions left over from last season. I look at the rosters, starters and reserves, for each team and try to see which team has the advantage at each position, etc. I don't generally try totals this early, because I really can't do it well without more current info on how teams are playing.
But, as for the MIL/NY Under, that's probably the way I would lean as well. Knicks can't run with the Bucks so they should take every opportunity to slow the game down. Also, since they're so understaffed right now, their starters get real tired and can't shoot towards the end of the game. Watch a replay of the 4th quarter of the 76ers/Knicks game and you will quickly notice how tired the Knicks get by the end of a game and how they cannot seem to score points down the stretch. For example, in the 3 games already played, their best player by far, Allan Houston, is shooting 54% in the first 3 quarters of games, but only 20% in the 4th quarters. If he's not scoring for this team, nobody is. Good luck.