Below you can find a checklist, which I wrote for my own purposes. It helps me to remember to check everything important before release a new version of R package to CRAN. Maybe you will also find it helpful.
[ ] Update this checklist.
[ ] Update the checklist version number.
[ ] See what new Hadley recommends:
[ ] http://r-pkgs.had.co.nz/release.html
[ ] Update R & packages:
[ ] R
[ ] all R packages
[ ] RStudio (stable or preview version).