Pipet tips for pipettors are available in many forms including universal tips. There are filter tips to avoid aspirating the sample into the pipette. There are gel loading tips with flat points for loading electrophoresis gels. There are autoclaveable tips, sterile tips, and rnase/dnase free tips. There are tips for robotic pipetting systems and positive displacement tips for viscous samples. Choosing the right tip for your pipettor is essential. Not all tips fit all pipettors, not even the universal tips. The best way to make sure the pipet tips fit your pipettor is to use the tips from the manufacturer of your pipettor. Not only must they fit your pipettor, they must have reproducible delivery of the liquid. The manufacturers of pipettors report accuracy and precision for their pipettors but these statistics are obtained with their brand of pipette tips. Most manufacturers of universal pipette tips will send samples of their tips so you can try the tips and see how they work for you. If precision and accuracy are important to your lab and you are not using the same brand of tips as your pipettor you will have to determine the accuracy and precision in your own lab.
Pipette tips are available in various forms of packaging. The most common is trays of 8 x 12 tips to accommodate multichannel pipettors used with 96 well microplates. Rack reloading systems are available to reload those empty pipette racks. These save waste and are more affordable than purchasing individual racks. Bulk bags of tips are the most affordable way to order and this is just fine for some labs.
If you are unsure whether a tip will fit your pipettor, ask for a sample.