The classic mountaineer's day out is to do the full horseshoe in an anti-clockwise direction. In anything other than full summer conditions parts of this can be intimidating and dangerous and in winter conditions it's pretty serious. In good weather a fit walker can do the horseshoe in 7 hours.
There are a couple of easier routes, notably alongside the railway. If you're going to pay for a railway ticket, walk up then train down because coming down is much harder on the feet and leg muscles.
Don't approach the mountain with a mobile in your pocket and the attitude that if anything goes wrong you can simply call for help. The climbing ethos in Britain used to be and still should be that you only undertook what you were capable of doing and you had the wisdom and experience to know when to retreat. Sadly this is no longer the case with many.
If you want somewhere cheap and climber-friendly to stay, I recommend The Heights hotel in Llanberis, which is an old Victorian hotel run by climbers. They have individual rooms and bunk rooms, great beers (maybe even some cooking lager if you insist!) and good wholesome food. It's within a few minutes walk of the mountain railway station.
