My tip for project management is to keep a diary of who's on site and what they are doing. Although I've got a security camera recording this it would have saved me lots of time if I'd kept a diary from the start.
My 'diary' now is a simple text file in a Dropbox folder that me or my partner (co Project Manager) update daily consisting of just a line per day giving which contractor is onsite, how many men and what they are doing. Takes about 30 secs a day to update.