onigoroshi:
I think somebody between 1400-1599 could win practically all their games against an average player off the street. Even as a youngster in Jr. High School, I could give many of my friends big odds like that of a Rook or even Rook + Knight after reading and studying chess literature for about a year. At that time I could not have been much more than a 1200 level player. My first USCF rating wasn't until I was a Freshman in High School and that was in the mid 1400s. The rating went higher later, but that of course took a lot of time and effort, maybe more than I should have put into it!

There are quite a few modern tactics books out there beyond Reinfeld. Jacob Aagard did one in his series of five instruction books. I personally think playing through complete games is also helpful and any game collection of aa famous chess player from Morphy to Kasparov would be helpful. "The First Book of Morphy" might be a good place to start. The games of older players are a little easier to understand and the mistakes often were a bit more obvious before defensive technique became more refined.