Graphic design can be a hard task-master at times but you don’t always need to pay somebody a small fortune to do your dirty work, with just a few simple rules you can create your own masterpieces (unless you have the money, in which case get a pro).

Keep it simple
One of the most common mistakes when you looking at mom and pop art, overly complicated designs confuse the eye and make your observer unsure of where to look - focus the attention somewhere. This goes equally for white space, just because that ad space cost you a fortune, doesn’t mean you have to fill it up - less is quite literally more.

Theme
Often forgotten - what is it that you are advertising? If your selling cute little Duracell bunnies, a gothic grunge font with a background of nails is hardly likely to get the message across! Try to put aside your personal favourite font and go with what’s fits with the theme - you’d be surprised how much of a difference this makes!

Graphics
Steer well clear of clip-art, I don’t care how good you think it is - it’s not. A simple well composed photograph will go a whole lot further than a load of clippings. Try to use just a couple of graphic elements - again, direct the eye to your message.

Typography
You can do an entire degree in typography so be mindful of the amount of fonts you are using and the complexity of type. Good designs have 2 or 3 fonts maximum. Often I’ll choose the title font first and then draft in the body text and fiddle with the font after I have finished the background plate.

Colours
Another very common mistake, keep to a colour theme, choose a base colour and then a subset of that colour - there is rarely a reason to use the rainbow of colours and less is more.

Compostion
This is always going to be a tough one to get your head around, but the more you design and observe others work (not that it will always be good) to more composition will occupy your mind. Being a film guy, I’m used to peering through a view finder and using the ‘Rule of 3rd’s’ for perfect composition - this technique transfers well from the movie frame to the digital canvas - that’s not to say that you can’t go against the general consesus and purposfully distort the frame - just make sure you have a reason for doing it.

Observation
It sounds obvious, but looks at other work by other ‘artists’. Look at how they have composed, typed, colours and edited the advertising space to get their message across. When you wandering down the street, take in the colours and geometry of your surrounding areas, try to visualise your surroundings on the 2d plane.

Bold
Don’t be afraid to be bold (unless your next job depends on it). Some of the most successful designers have taken a well established concept and turned it on its head. Personally I think that alot of work has obvious hallmarks with regard to its quality - one mans rubbish is another mans treasure, but sometimes you have to just wipe the slate and start again.

These are just my own personal views on the subject. Everyone designs differently. Expect to take criticism, but take it well for sometimes we are wrong and what may appeal to a designer might not to the mass populace.