Take a look at the blog "lambda-the-ultimate.org", there is a thread on the sidebar called "getting started". There's links in there to several good resources (Types and Programming Languages; Structure and Interpretation of Computer Programs; Concepts, Types, and Models; Essentials of Programming Languages; etc).
Also: Start off by not thinking about syntax at all -- in fact, take all syntax out of your language. Break it down to the key concepts you want, such as how data is manipulated, what makes the program flow, etc. To do this, make your first stab either in a prefix-style language (Lisp, Scheme), or postfix-style (Postscript, Fourth, Factor). By minimizing the syntax you can figure out what makes your language different. Then start adding syntax back in.
If you take the approach of picking syntax from various languages and putting them together, it is kind of like taking pieces of several songs that you like, and trying to make a really good song out of those. Doesn't work as well as writing a new song from the bones up.