Don't forget though, Do-It-Yourself can save you money but if you're not committed to doing a good job, using quality products and preparing properly you could just be asking for more stress and most likely further costs. In this case we would always recommend using the professionals and paying good money for a job well done!
Invariably preparation is the key to a quality finish. If you're painting an inside wall you need to smooth it down with sand paper and dust off with a soft brush. If you are painting wood, an outside wall or a greasy inside wall (kitchen) you will need to wash the wall first. It's important to clean the wall before smoothing; doing it the other way round will only result in rubbing the grease you should have cleaned off deeper into the surface. Sanding down not only removes imperfections in the wall but when painting woods it also creates small grooves for the paint to latch on to.
Dimming the lights in the room and using a torch to look down the walls will highlight any raised areas which you should attack with the sand paper during the smoothing process.
Oil based paints don't dry very quickly which makes it easy to paint with and to make amendments or smoothen because the paint will still be wet. Naturally this means it takes a long time to dry though - usually overnight.
Acrylic/water based paints however dry quickly so you only have a small window of time to get it right. This is an important factor when you consider that you should never paint over the top of somewhere you have painted already if the first layer is dry.
Remember that preparation is the key! The moment you start painting means the light is at the end of the tunnel and most of the work should now be behind you. Make sure you have a system before hand, start in a corner and work logically around the area. New walls will invariably need 2 coats.
When joining corners or painting the edges first be very careful. If your joins overlap you may double up over already dry paint and this will be visible. It's these subtle techniques that make the difference to a professional finish.
Generally outside surfaces are exposed to the weather which makes oil based paints a much better option. When working outside you must make sure everything is dry. Likewise, you should generally avoid painting in the evening - or at least stop in time so that the paint will be drying before the moisture of the evening.
If your outside surface is getting bubbles in the paint there could be two reasons for this. Either because it's not clean enough so the grease is stopping the paint from latching onto the surface or it has moisture trapped inside it. In the later the moisture is evaporating out of the material and pushing the paint off the surface from underneath. To remove the bubble to must remove the paint with a scraper, re-clean, dry, sand down and then paint again.
If the wood you are painting is rotten, you must repair it first. You need to use a 2 component filler for this because it's stronger and gets tighter into the wood. If the rotten wood is moist - you should remove all the moist wood by hand first. You can then seal what is left behind with a sealer and then use a filler to fill the hole. Level and smooth the filling straight away while it's still wet and afterwards use sand paper once it's dry. After that you should use a primer before painting.
Check if is dry enough outside by looking at the cars in your drive if there are water drops then it's too wet. Any part of un-protected outside wood that is exposed will allow moisture in over time. This will create bubbles in the future. Doors must have their bottoms painted to avoid this.
It's always advisable to spend on good materials -this is a professional's main trick for a quality finish! Quality paints have better base materials and pigments and the brushes work cleaner and don't lose bristles.
Preserving your bushes is also important to retain their effectiveness. When using oil based paint use white spirit and then warm water with a gentle washing liquid. Store them in a jar with linseed oil or sunflower oil.