This is one of the earliest mosaics I ever made - It is so so simple. You get to work with colour, placement, and grout though, so it is a nice introduction :)
I will post up a more complex project soon :)
The first step is to get some of that pva glue, dilute it and spread it all over the surface of your mirror frame. This will stop the wood from warping when you grout it later.
When that is dry get your tiles, and start by laying them on without glue - you'll want to work out how many tiles will fit length, and widthwise. Play with the gaps between tiles if you find that you can't quite get the tiles to fit - but don't let the gap get bigger than 2 or 3 mm... It is important that whatever the gap you choose , you are consistent with it.
Think about adding a row of beads or similar, if needed. Once you are happy about how you need to place them:
Start gluing tiles! Keep stepping back and looking at what you are doing - try to get a balance of colours and shades. You can spread undiluted pva glue over the area you are working on, or have a pot, and dip the bottom of each tile into it as you go along - whichever suits you best :)
With this mosaic I mixed up random placement of the hues of green and purple/brown, with regular rows of the two colours.
Arrange them in a way that makes your eyes happy :)
Keep gluing until you have covered the entire front surface. Set it aside for a while and let the glue dry.
Pick up the frame, once dry, and give it a very gentle shake. Glue back any tiles that fall off :)
Next is the messy bit - grouting.
Please use protective equipment! Grout will dry out your hands, and can be harmful to your lungs, please use gloves and a mask.
Mix the grout according to the manufacturers instructions, and spread on the surface - I generally use my hand and gently rub it into all the gaps. Don't forget the edges too.
A tile or three may fall off - just place them back in and bed them down with more grout :)
Give the grout a short while to dry - not more than five to ten minutes - and get your very lightly dampened sponge and start to clean off the surface.
Use your bucket to clean off the sponge - and any grout that gets on you - Grout will block drains if it is poured down a sink or toilet, so you don't want to do that :) Just wait until the sediment has settled, and you can pour off the water outside.
Please be careful when using glass - even with a simple project like this one, tiles can sometimes be chipped, so go soft and gentle, and take care :)