I think that during the Revolutionary War soldiers who joined the Continental Army were recruited through one or more of the three following methods: 1) patriotism, 2) drafted into service, 3) to defend their homes and rights, and 4) the promise of good pay and land. I also know that the British army were able to recruit soldiers through patriotism (ex: loyalists) and impressment, but what about pay? Were the British able to attract new recruits through promises of good pay and land? And how much were British soldiers paid compared to a soldier in the Continental Army?
At the wars outset a private in Continental service earned 6.67 dollars per month. This number would jump around significantly throughout the war, and lack of money, paper or coin, to pay the men with, plus obscene inflation of Continental paper currency makes it really hard to pin down the purchasing power of a private soldier from one year to the next. This is part of the reason why you see enlistment bounties (bonuses) that could include some combination of a little hard specie, a lot of paper money, livestock, land, and clothing. Some units, especially later in the war, had serious problems with men enlisting, taking the bounties, the deserting to repeat the process elsewhere with a other unit. Another issue Continental troops dealt with sometimes was simply not being paid at all, which was one reason the PA line attempted a mutiny at one point.
A British soldier on the other hand earned 8 pence per day. At a rate of 12 pence = 1 shilling and 20 shillings = 1 pound, that's about 1 pound per month, and about 12 pounds per year. This is definitely on the lower end of 18th century British incomes but is by no means unlivable. British soldiers have the advantage of receiving their pay in hard specie, which unlike Continental paper money, is not subject to wild devaluation essentially overnight. The downside to the British system is that their troops are subject to stoppages, which is when your pay is docked to help pay for equipment or other necessaries. In extreme cases stoppages can be levied over all manner of tiny little things, with a mutiny nearly breaking out at Fort Michilimackinac over a stoppage on hair powder (straw that broke the camel's back situation.)
It's worth mentioning that the British army of the revolution was almost entirely volunteers, with impressment largely restricted to the navy. There is a brief attempt mid war to impose conscription, but to get it passed through parliament there were so many restrictions on who could be conscripted that they ended up just giving up on it entirely. This is part of the reason why subsidy troops like the Hessians were so important to the British war effort, there just weren't enough soldiers to go around.
Best source for British army recruiting and training is the book "fit for service." American information is so inconsistent from year to year, unit to unit that there isn't really any one single definitive source to look at.