where do you live? finding a course is a great way to get started.
for a simple indoor mosaic you need some plywood cut to size. use stuff that is a minimum of 1cm thick. the thinner stuff will bend, and the thicker will just add to the weight of the finished piece.
draw on your deign. pencil is best as you can rub it out if you don't want it to show through any clear glass or tiles.
don't get too intricate with your design either. big bold shapes work well.
use kitchen tiles or mosaic tiles or stained glass or mirror, shells or beads or anything else you fancy. if you want it to be smooth and flat when you finish remember that if you use details beads etc you'll have to scrape out all the grout to make it nice again, so save yourself the effort
cutting depends on what you are cutting.
ordinary tile nibblers are good for ceramic kitchen tiles and are pretty good really for glass tiles too.
if you get into it, it's worth investing in some mosaic cutters that have cutting circles for a nice clean cut.
mirror and glass tends to chip a bit, so the next stage is learning to cut the glass with an oil scorer thing and glass splitters. (not recommended for a first project as they are expensive and a bit tricky and might put you off)
glue your pieces on using waterproof pva.
simple.
get a glue spreader for this from kids art supplies places.
when it's finished then you grout.
grey always looks good. you can get light grey grout from most hardware places.
white can look a bit cheap.
you can colour white grout with acrylic paint. but if you want a bold colour you can buy special coloured grout. black looks amazing.
remember to use tile colours that will stand out from your grout.
mix it up, plop it on, panic that you'll never see your mosaic again, rub it into the spaces, wipe it off the surfaces.
next day give it a jolly good clean.
tada.
i'm on here regularly though so if you want talked through each stage i'll be here.
(although i should be mosaicing )
i get lots of tiles and glass from opus mosaic in exeter. they also do mail order.
have a search for local suppliers to you.
seconds of ceramic tiles are ideal for this.
how's that?