The most important trick I wanted to share is to try to roughly even off the top of the cake and then flip the cake over so the bottom (now nicely flat) becomes your top. This is key to make a cake that looks visually appealing. You then fill your cake with whatever suits your fancy - jam, lemon curd, hazelnut, chocolate fudge, etc. Place your second layer on top UPSIDE DOWN again so you have a nice flat top to ice. Dollop your icing all over the top before spreading it - this ensures you don’t get crumbs on your icing. Put extra icing on the top so that when you smooth it out it falls down the sides so that you also do not to get crumbs in the icing on the side of your cake.
In the picture shown I’ve also added a final layer of fondant on top of the buttercream icing. Fondant is the smooth hard icing that you roll out like pastry and lay it on top of your cake. Normally its reserved for decorating wedding cakes but I also use it for birthday cakes as well. To finish the cake simply wrap a ribbon around the bottom in either a similar colour as the icing or a striking contrast colour and secure it with some royal icing.
Voila ! You have yourself a perfectly styled cake !