The good news is that other than your time, setting up a turntable properly doesn't need to cost a huge amount. You simply need to work carefully and attentively to make sure your deck delivers the maximum performance it can. So, here's a quick walkthrough on how to set up your turntable for its best performance:
Turntables have many areas of setup but one aspect absolutely vital to their performance is the surface they have been placed on. Vinyl is very sensitive to being placed on an uneven surface. The effect of having the platter at an angle will vary slightly depending on your turntable but it is unlikely to be beneficial. With belt drive designs, the position of the motor relative to the gradient can introduce pitch instability and with heavier turntables, the 'flywheel' effect that they make use of can be interfered with. This can then present itself as audible wow in the audio signal. In extreme cases, really radical angles of lean can create excessive wear on your records although I stress, this will only be at fairly radical angles of attack.
Unlike any other part of the setup in this guide, the solution for rectifying this does not involve making any changes on the turntable (with one inevitable exception I'll cover in a moment). If the deck is not level- even if it has adjustable feet or the like to level it- you should make every effort to level the surface that the turntable is on rather than adjust the deck itself. If you are using an equipment rack or similar, you need to level the whole thing. If the turntable is on a shelf and this isn't level, you need to either do it properly or accept your limitations and have someone do it properly for you.
The partial exception to this is with a turntable with suspension that suspends the platter. If your plinth or chassis is level and the platter isn't, you will need to level the platter using the suspension of the turntable.
Turntables are sensitive to the outside world. On a basic level if you have a suspended floor and bound across it to your deck, you are likely to see your stylus jump. On a smaller level, the effect of your speakers and other external sources of vibration on your equipment will effect the performance. The signal from a cartridge is tiny and additional noise being recorded by the stylus through unwanted movement is extremely undesirable.
The absolute foolproof means of getting shot of this interference is a wall shelf (provided of course you have paid attention to the first section and fitted it level). Connected to a solid wall, the turntable will be effectively isolated from the goings on in the rest of your system. If you can't do this, there are some other options available to you. A simple isolation platform will do wonders for decoupling the deck from the rest of your electronics. Any solid material with compliant feet that gives the required isolation will work wonders. The ultimate expression of this is to take two paving slabs and a bicycle inner tube. Inflate the inner tube and use it to separate the two slabs. While the result is rarely very pretty, it is extremely effective. If all this seems a bit excessive, something as simple as Vibropod feet at $6 each can work wonders. Heavyweight and suspended decks are less affected by outside influences but it is very rare that isolation will have a detrimental effect.
A tonearm serves to both move the cartridge across the record and to apply the correct amount of tracking force to the cartridge. This force is rarely very high- the vast majority of cartridges don't need more than two or three grams to function but setting this weight correctly is critical. Set it too light and the cartridge won't track correctly and frequently sound thin and bass light. Set it too high and the sound can be dull and muddy. If the weight is wildly out, you may find yourself damaging the suspension of the cartridge and breaking it.
If your turntable has come with a cartridge pre fitted, this should not be too much of an issue but if you are changing the cartridge or assembling a turntable for the first time, you will need to make sure your weights are correct. To do this with real accuracy, you will need to use a stylus gauge. This acts like a tiny pair of scales to give you the exact weight at the stylus. The weight is changed by moving the counterweight at the rear of the arm. Unfortunately, this is an area where 'close enough' isn't going to fly. If the cartridge requires a given weight, it should be set to that weight and not an approximation of it. Some cartridge manufacturers supply a stylus gauge with their models but $30 buys the Shure SFG-2 which has been in production for eons and will last you a lifetime.
In order to sit in the groove of the record correctly, a cartridge is angled to move across the record in a tangent. While the end of the arm is angled to put you on the right sort of lines- and once again, if the turntable comes with a pre-fitted cart it will be aligned, if you are fitting one for the first time you will need to line it up. The good news is that you can download almost any protractor for any deck and arm. When in doubt, check with the manufacturer as to the alignment method they prefer and if they have a protractor that they recommend.
Alignment is something that gets people weirdly argumentative with advocates of one system frequently claiming that other techniques are compromises or somehow flawed. The reality is that all methods are a compromise to keep distortion as low as possible so select the one that works the best for you and your equipment. Take your time and make sure that the cart is correctly aligned- your records and your ears will thank you.
With turntables and tonearms designed to accept a variety of cartridges, the vertical tracking angle- the height of the arm above the record can- and should- be adjusted to ensure that it is a consistent height from front to back. Altering the angle that the stylus hits the record will once again affect the bass and treble depending on whether the arm is tail up or tail down. The amount of adjustment that an arm will allow for does vary so if you are matching an arm and a cartridge, do check the size of the cart and make sure you can get the necessary elevation on the arm.
All this can sound deeply intimidating for a beginner but in reality, each process is logical and relatively straight forward. Don't rush, don't lose your temper and don't cut corners. The good news is that most turntables tend to stay where they are once you have put in the legwork and I promise you that the difference between a turntable that is correctly setup and exactly the same deck that has been casually plonked down somewhere should be enough to have you putting a little bit of effort into getting the best out of what you've got.