How do I use my lever press correctly?
Because manual machines work under the same premise as automatic machines, you can follow the standards for a normal espresso. Id suggest looking at other guides to making a good espresso, or even watching how the espresso is poured at your favorite cafe. 

Consistency

The ideal consistency for espresso should come out between a pour and a drip in what I'm coining a half-drip. It should look like this:



Brew Ratio

The standard brew ration for an espresso is 1:2 - 1:1.5, 1.5-2 grams of water for every gram of coffee. Since a double basket is usually about 18g of coffee, you should aim for about 27-36g of espresso.

Since every manual machine is different, you'll have to play around to see how many times you need to pull the lever to get the right amount of espresso. This also means if you have a bigger basket, you will need to pull the lever down more times to get a similar shot.