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It's truly an art form. There is no one way.
CR is a good place to start, but other factors need to be applied. Some groups perform better than "average" and can face higher CRs. Some groups perform worse than "average". Some monsters seem to be set at a CR that is a little bit off - these monsters perform above or below expectations for their listed CR, but knowing which ones is hard (some forum threads can help with this).
External factors can affect the encounter such as special terrain, hazards, and the PCs' depleted resources (a party can handle any specific encounter first in the day more safely than the same encounter last in the day).
And possibly the hardest part is that none of this is set in stone. It's possible that one party of four PCs can handle a particular encounter and make it look easy, but a different party of four PCs of the same level but different classes might have a very hard time with that same encounter.
For me, I look at all of that stuff.
For example, right now I'm GMing a party of five PCs that are all 4th level, so all the encounters can afford to be higher CR than 4. Sometimes I have larger numbers of weaker encounters, sometimes smaller numbers of tougher encounters, but CR 5 is a good baseline for me right now (they almost just died to a CR 5 Phase Spider this week; that poison is NASTY at their level). Right now the highest damage dealer we have is a blaster sorcerer heavily focused on fire damage. If I throw a CR5 monster at them that is immune to fire, this group will have a hard time dealing with it (they have a warpriest and a dervish who can both deal OK damage so it wouldn't be a total loss), while if I throw a CR5 monster that is vulnerable to fire the will kill it instantly. So if I want a fire-immune encounter, I might go with CR 4, or if it's fire-vulnerable I might go with CR 6 or 7. If it's the first battle of the day I might add a CR, while I might subtract a CR for the last battle of the day. Etc.
But in the end, I usually just decide what CR I want based on resources and terrain, then pick something cool at that CR, then evaluate whether it has special qualities that make it harder or easier based on my current group of PCs, then maybe adjust it with a template or a couple bonus feats or some such.
The CR system is a very loosely-based one. It won't get you what you want every time. Some trial and error will help you alot along the way, if you're new to this sort of thing. The most important factor to take into account would be the party make-up of course.
For instance in games that I run, if the party doesn't have a trap-spotter, I usually don't involve traps during a dungeon delve, unless it is one they can overcome by their own means.
For a better exapmle, a Clay Golem (CR 10) is a "tough" encounter for a level 7 typical party (Fighter, Cleric, Rogue, Wizard). However, it is a "nearly impossible" encounter for a party consisting of a Caster-Cleric, a Magus, an Enchantment based Sorcerer, and a Ranger who is outside of his home turf.
To answer your question directly, it's best to tailor the encounter yourself.
I use this (Link here). To summarize, you calculate encounters by XP instead of CR. It's the only thing I really use XP for.
Yup! I gave up on XP awhile ago and haven't looked back. The difference between using it and not using it is rather minuscule anyway. The GM is going to tell you when you level up either way, be it by advancing the plot or by telling you a certain number to add to the number on your sheet, and you find out yourself.
I find that looking at team compositions versus the general enemies you expect to throw against the party is the best way to determine a balanced encounter. For example, I ran an all bardic campaign, and knew that I could only throw small amounts of undead at the party, as they were not as well equipped to fight them as other creatures. From there, look at what the creature has and see if that would cause too much strife or too little strife for the party, and balance from there.
As stated above, it's something that gets easier over time, but the number 1 rule of planning encounters is to know the rules for those monsters very well. You want to make sure that if something bad happens it wasn't because of a misunderstanding of the RAW.
I've tried using the CR system however i feel it either creates extremely easy encounters or nearly impossible encounters. If I just tailor each encounter ignoring CR i can usually gauge it correctly. I'm just curious how other DM's make balanced encounters.
Just don't balance them. Read these Alexandrian blog post for why fetishizing balance is not needed:
Revisiting Encounter DesignFetishizing Balance