I always recommend that when new brewers are starting off, they follow the instructions of the kits..ANd they don't alter the recipe by adding stuff like fruit or spices to THAT recipe or kit...that if they want a "cherry chocolate coffee stout" rather than buying a stout kit and trying to figure out how much cherry, chocolate and coffee they need, that they actually just buy the Cherry Chocolate Coffee Stout kit instead...
The kits are nearly fool proof, which means if, you can concentrate on your brewing process AND if something goes wrong (which is rare) you're more easily able then to examine your process to see where you messed up, and can improve the next time you brew...If you go "off the reservation" and randomly start changing either the recipe or the process, you really run the risk of first throwing off a balanced recipe, and secondly and most importantly
not really being able to figure our WHAT went wrong should the beer not turn out.
If the beer tastes yucky, you won't be able to tell if you screwed up your process (like your sanitiation, let's say) or because you altered the ingredients in the recipe and through of the balance.
I say that before people start changing things willy nilly..They .actually LEARN about what the ingredients do, how recipes are created.And how the process (like length of boiling time) affects the final product.
Brew a few kits or recipes "AS IS" before you start tinkering with them...coming up with a balanced and tasty recipe takes some understanding of things...just like cooking...dumping a cup of salt will more than likely ruin a recipe...so if you cook, you KNOW not to do that...it's the same with brewing...you get an idea with experience and looking at recipes, brewing and playing with software how things work..what flavors work, etc...
In other words work on your brewing process FIRST...and least for the first 5 or maybe 10 batches...Then you will have better idea of what effect your "playing" will have on the other ingredients. Stick with the kits, and follow their instructions, at least initially.
It may not sound very exciting....but you WILL get a good final product...If you plan on doing this hobby for a long tike like most of us, there will be plenty of batches of beer, and plenty of time for experimentation....