Once I am satisfied with how the wood stacks up, no warpage in the boards where there is big air gaps (ie avoid warped wood). Then it's time to glue!
I lay out the pieces of wood in chronological order on the table as I need to work quickly during the glue up phase. This means I have all the tools I am going to use  ready on my work bench. And I like to do a glue up on top of card board as it is a messy process.
I then pour a squiggle line of wood glue across the piece, use a scrap piece of wood or cardboard to spread an even layer of glue across the piece.
Once all the pieces have had glue added to them and they are re stacked up in chronological order I attach a lot of clamps to the piece. If there is a gap of the wood not touching that's a pretty good indicator you should put another clamp there. 
What I do not have an image of is using a sponge and clean water to mop up the glue that pours off the side. You want to mop up excess glue off of the wooden piece, clamps, work bench etc...

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• Wood Glue
• Variety of Clamps
• Scrap scraper
• Cardboard
• Water and Sponge

Jig Saw