I don't seem to have much of an issue with spam.
Perhaps 4 or 6 a day.
My ISP does not block spam.
I don't run a spam blocker.
Some things that might help a little.
Be malware free.
Chose an addy that's not such an easy hit for the spammer's mass mailers.
Don't open or respond to spam.
Be careful where you post your addy...public boards are spam magnets.
I'll get about 2,000 spam messages a week that Yahoo blocks, and it doesn't catch about 4. Am I the only one with horrendous spam problems?