Writing style:

- Ten Simple Rules for Mathematical Writing by Prof. Bertsekas
- Prof. Cole Smith’s “Writing tips and style guidelines“
- The Elements of Style, Fourth Edition by William Strunk Jr. et al.
- How to Email Your Professor (without being annoying AF)

OR/CS/Math blogs:

Data visualization packages:

- Graphviz
- dot2tex is a LaTeX-friendly converter from Graphviz (xdot) to converting xdot PSTricks or PGF/TikZ commands, with support for LaTeX labels and arrows. [Kjell Magne Fauske]
- Online graph generator

Useful tools:

- Convert Excel to LaTeX tables
- Convert PPTx to Latex
- Free Python Optimization Packages, among which SCIP is currently one of the fastest non-commercial solvers for mixed integer programming (MIP) and mixed integer nonlinear programming (MINLP)

Others:

- Drs. Mark Dredze and Hanna M. Wallach’s “How to be a Successful PhD Student“
- Seven secrets of highly successful research students