1. Use a good recipe
For sure and correct results it's important to follow baking recipes to the letter so your cake will only ever be as good as the recipe you use. Start with a recipe from a source you trust. A lot of recipes, particularly on the internet, haven't been tried and tested (I suggest you got for mentoring from a certified baker)
2. Use the exact size of pan as stated in the recipe and line it well
If you want to use a different one then you'll need to adjust the cooking time.
Parchment paper works really well for lining because of its non-stick nature. Softened butter dusted with flour, or oil dusted with flour, are alternatives. Don't use too much fat though or you'll fry the sides of the cake. If you're cooking a cake for a long time (rich fruit cake, for example), it's worth wrapping the outside of the pan too using brown paper and string to stop the edges from burning. (Now make sure the oven light does not get to the paper)
3. Preheat the oven
If you put a cake into an oven that is not hot enough, it will affect the way it rises. Fan ovens can dry a cake slightly so for a longer shelf-life use the conventional setting.
4. Be accurate with your measurement
Make sure you use the exact measurements and ingredients as stated in the recipe. You can't just add more baking powder if you want your cake to rise more or substitute self-raising flour for plain. Use measuring spoons rather than table wear to ensure accuracy. Also, avoid mixing imperial and metric measurements, pick one or the other.
5. Make sure ingredients are at the right temperature
Most recipes require the fat and eggs to be at room temperature. If you take the butter straight from the fridge it doesn't cream well and cold eggs are liable to curdle the cake mixture.
6. Get as much air into the cake as you can
Cream butter and sugar until the mixture lightens in texture and color. This act increases the air and volume of the cake, giving you a lighter result.
Sift flour and other stated ingredients together to mix, add air and make them easier to fold in. A large balloon whisk (used gently) is best for folding as it helps to avoid lumps of flour but doesn't overwork the mixture. Don't be tempted to whisk vigorously as this will knock out the air and result in a heavy cake.
7. Once the cake mixture is made put it straight into the oven
The raising agent will start working as soon as it comes into contact with any of the 'wet' ingredients so to ensure a good rise your cake mixture should go into the oven straightaway.
8. Put the cake on the correct shelf and keep the oven door closed
Cakes are generally best placed on the middle shelf to ensure even cooking.
Once the cake is in, avoid opening the door until it's almost cooked. If you allow cold air into the oven the cake is likely to collapse, you need to wait until it's properly set before taking a peek. Similarly, when you're putting the cake into the oven, don't hang about and let all the heat out.
9. Stick to cooking times
If you've used the right pan and you've got a good oven, the timings stated in the recipe should be accurate. As ovens do vary, check the cake just before the end of the cooking time. A cake that is cooked through should feel the same if pressed around the edges or in the middle. Also, a skewer inserted in the center should come out dry. If your cake is not properly cooked but looking brown, you can cover it with a bit of dampened grease-proof paper.
10. Cooling cakes
Recipes will usually give instructions for cooling but as a general rule, most sponge cakes are best left for a few minutes and then turned onto a cooling rack to avoid soggy edges. Rich fruit cakes are better cooled in the pan.