Nucleophilic Strength Guidelines

[Junghyuk_Park_1I]

What are the general guidelines/rules for determining nucleophilic strength? Electrophilic strength? The textbook notes some rules, but it also says that the rules are not definitive so I am a bit confused. Thank you in advance!

[Hung_Sabrina_3N]

If a nucleophile has a negative charge not a partial negative charge, the more negative the charge is, the stronger the nucleophile. After will come the nucleophiles with partial negative charges due to difference in electronegativity, last will be nucleophiles with the lone pairs or double bonds present in the molecule.