Do some research, and look to see whichever one is most comfortable for you.
Wether it has to do with the look of the crystal, the properties, etc. It's your choice. It can also depend on how much energy it's giving off (depending on if you're near the crystal). If you don't feel a connection with it, feel free to keep looking until yo find the crystal that's right for you.
*I can recommed you to some of my favorite crystal shops if you'd like*
Here's an article on SoM about some of the different crystals and their properties:
do you have access to pictures of crystals?like in books?
do you feel energy from crystals yet?
if that's a yes and yes,try waving your hand over the pictures asking if this is the crystal you need.i have been able to feel energy from the pictures of the crystals i need.it sounds crazy,but it works.
When working with crystals its best to do your own research. But if youre just starting out I wold suggest getting quartz and you can charge it with any intention and its a very good tone to use. I hope this is helpful :)
I agree with Freya. Quartz is a good stone to connect with as a starting place. Quartz has many varieties to learn about, so there is lots of room for study. Quartz is also incredibly common and easy to find. It's dirt cheap too. You can get a nice-sized clear quartz for five or ten dollars.
For practicing energy and crystal working, clear quartz is best for starting because it is easy to connect with, and it is easily programmable. It's like a blank piece of paper; ripe for the drawing. Amethyst is good if you want to focus on healing energies as well.
Blue kyanite is another one that is easy to get. It is similarly priced to quartz, and is an overall potent stone. It doesn't need to be cleansed or deprogrammed like quartz, and in fact acts as a cleanser for other stones when they are placed together. Kyanite promotes attunement and energy alignment. Simply having someone gently run the stone along your spine from the top of the head to the end of the tailbone and back up again can realign one's promary meridians and stimulates energy flow. ... Some people are more sensitive to this stone than others though, and can feel buzzy or tingles when handling it. If you feel wonky working with it, there are less intense stones out there you can work with until your system gets more comfortable with things.
Clear quartz is a wonderful multipurpose stone. I'd start out with the quartz family (amethyst, clear quartz, smoky quartz, Rose quartz, citrine, calcite, blue quartz fire quartz etc.) they tend to be safer easy to care for and great beginner stones. Just don't leave them in the sun, the colors can fade. (some stones like howlite and fluorite though pretty, and have wonderful energies can be dangerous to handle for extended periods of time due to levels of toxic elements such as Florine or arsenic.) so just do your research be aware and try to find which stone suits you the best :)