Ask HN: Going freelance. What are your best advice to new consultant?

I am going freelance consultant as of 6/1 -- I am excited yet nervous.<p>What are your best tools for keeping your self organized, managing client info/time/data/etc?<p>I am a health care systems design consultant - not a developer. Ill need to track time spent, just found Toggl. and invoice etc..<p>What do you do as a consultant?