WinKey+R start typing name of program
In other words, exactly the same way you could invoke them in W7. This doesn't work for everybody, but this works for me because I could never be bothered to organize the Start menu and so when I tried using it I was always hunting through sub-folders; since my hands were usually already on the keyboard to begin with the search method was faster.
Also, you can pin frequently-used programs to the task bar exactly like you could in Win7 (which was the other reason I could never remember my Start menu layout: 80%+ of the programs I used everyday were already pinned -- or still running from where I left them the day before -- meaning I didn't touch the Start menu at all).
If you really want a Start menu replacement, there's a couple out there and a thread about them
already. (Here's another thread
you might find useful as well).