Well, I can speak for the Napoleonic era through into the middle of the century.

Usually soldiers were recruited through 3 ways. The first and most 'romantic' method, was to join up after being recruited by a recruiting party led by a Sergeant that would travel around the towns and countryside in circuits, usually dressed in theatrical versions of the regular Army uniform to look as splendid as possible, who would regale prospective soldiers with tales of the benefits of Army life and the heroism, and appeal to the ladies the life provided. As each party recruited for a particular regiment, they would focus on the battles and honours the particular regiment had earned and so some young men who wanted to join would express preferences for particular regiments, with the Guards regiments being held in the highest esteem, followed usually by the Cavalry, and then certain Infantry regiments (particularly those with many battle honours) being favoured, with those regiments stationed in unpopular places such as the East or West Indies being the least attractive of them all, due to the likelihood of death by disease. Due to the unpopularity of the Army with many people as a career, many Sergeants would get their potential recruits heavily drunk in the local taverns before getting them to sign up, then locking them up to prevent their escape upon sobering up.

A second method was the recruiting Sergeant would consult the Justices of the Peace and Assizes Judges in each parish and Hundred, and would recruit for a fee those persons found guilty of petty crimes not sufficiently bad that they had been sentenced to transportation or death, as there was no formal prison system. It was with respect of this group that Wellington referred to the soldiers of the British Infantry as 'the scum of the earth'.

The third main enlistment route was for those who transferred from the Militia (the part time home defence army who were not obliged to go on foreign service) to the regulars. There were several inducements for those willing to transfer such as being able to pick their unit (where practical) and signing on bonuses of anywhere up to £30 (equivalent to 2-3 years pay for a farm labourer) at the height of the Napoleonic wars, due to the benefits of their previous training being highly valued

Those who transferred or volunteered would often also receive a bonus for signing up, ranging from £7 to over £23 though often the stoppages in their pay for the price of their equipment (which they had to pay for themselves) would wipe out much of their bonus upon joining the Army.

The ceremony would be finalised when the recruit took the 'King's Shilling' as a symbol of their joining the Army, and signing their recruitment papers, either for 26 years, or from 1807, there was the option of joining up for 7 years.

The pay throughout the first decades of the 19th century was 1 shilling per day (12 pence), but the soldier had to pay for their food, clothing, rent and pension contribution to the Chelsea Hospital fund from this, leaving many soldiers with £7 7s 7d as a basic yearly wage, less than an agricultural labourer of the time, but at least with the guarantee of food everyday.

On foreign and campaign services the living conditions could be terrible, as the quartermaster's department was usually very inefficient at providing more than the most basic necessities, and tents, being heavy were often left behind or rapidly abandoned, leaving the soldiers to sleep under blankets in all weathers. For more details of this aspect of soldiers lives I recommend both Redcoat by Richard Holmes or The Armies of Wellington by P. J. Haythornewaite.

On home service the idea of military barracks was only just starting to come in, so the majority of Soldiers through the Napoleonic period were billeted in taverns or in camps.

This should cover the basics of your questions, but feel free to ask any follow-ups if you want me to expand on any points.