This is from the other page i saw so have a look at it and then you can write you own.
This is for information :) :
We often get asked for tips on painting the MDF shapes so we hope you find them helpful! MDF has a smooth finish and is one of the easier substrates to paint to get that lovely finish. Whilst we prefer a satin finish paint, it is your choice although the spray cans are very easy to use and you can get them from the large major DIY stores. They can also be used on our plain unpainted wooden boxes, after priming. These tips can also be used on birch ply although it is not as porous as MDF and a primer will be adequate.
1) MDF is very porous and must be sealed before painting.
2) MDF Sealer is available ready to apply although a standard PVA glue mixed 2 parts PVA to 1 part water does the same job.
3) Lightly sand after allowing the sealer to dry completely.
4) Apply a second coat of sealer if required.
5) Lighly sand after allowing the second coat of sealer to dry completely.
6) Spray cans suitable for wood can be used to give a smooth finish
7) Apply light coats and gradually build up the colour to avoid drips.
8) Or: Apply acrylic paints with a brush or small roller.
9) Allow to dry completely between coats.
10) This gives a good base finish to apply further decoration.
If you would like to paint by hand on the MDF use a spray can either in gloss or satin to prepare the base colour. After hand painting your design with acrylic paint you will need to apply a light coat of spray lacquer over the top to seal the acrylic. Make sure that you allow the paint to dry completely between coats before spraying with the clear lacquer or you will experience ‘crackling’.