From Spurgeon's book: All of Grace
Do not attempt to touch yourself up and make yourself something other than you really are, but come as you are to Him who justifies the ungodly. …The Gospel will receive you into its halls if you come as a sinner, not otherwise. Wait not for reformation, but come at once for salvation. God justifieth the ungodly, and that takes you up where you now are; it meets you in your worst estate. Come in your disorder. I mean, come to your heavenly Father in all your sin and sinfulness. Come to Jesus just as you are: filthy, naked, neither fit to live nor fit to die. Come, you that are the very sweepings of creation; come, though you hardly dare to hope for anything but death. Come, though despair is brooding over you, pressing upon your bosom like a horrible nightmare. Come and ask the Lord to justify another ungodly one.
And here's a paper I wrote on how to preach evangelistically to sinners without demanding repentance first.