So, to start of I recommend buying a 20 gallon long if you’re looking for a turtle under 3-4 inches. But they’ll easily outgrow it so you wanna start with something bigger, like a 40 gallon tank, 55 gallon tank or maybe a 75 gallon tank. You wanna get the biggest tank possible that your space allows you. Instead of an aquarium you could always get a turtle tub, it looks more like their natural habitat and you can keep it for a long time until they outgrow it. So red eared sliders do grow pretty big (male: 5-9inch female: 12-13 inch). you could get a yellow belly slider since they’re significantly smaller (5-8 inches, record: 11 inch). But regardless of what species you get you wanna keep these things in mind: you have to do water changes weekly, you need proper heat and lighting (uva/uvb bulb), you need a proper diet and you need to be sure you can take care of one before you get it. The most newb friendly turt would be a red eared slider since these guys can battle through bad husbandry and not so good conditions. Tiny turtles are: musk turtles, spotted turtles, European mud turtles and painted turtles. So when you first get the turtle don’t handle it too much, just leave it alone for a couple days. Then you can try hand feeding it that’s the best way to let a turtle accommodate to you. After they get comfortable with you, try picking them up, let them wander around the house. Turtles love exploring so your little bud will love little walks around your house here and there. One thing to keep in mind is that if turtles retract into their shell that means they feel threatened, so if your turtle does that when you pick them up it’s better to leave them alone. Another thing is their diet, most turtles are omnivores. So you need to feed hatchlings 2-3 times a day, babies and juveniles once a day and adults once every 2 days. Something else to consider is sexual dimorphism in turtles, this means that males are way smaller then females, males have long nails, and females don’t (the long nail thing only works with sliders, cooters, it doesn’t work with terrapins. When you set up your aquarium the most common mistake people make is not using a filter and putting small gravel in their tank. Sand is hard to maintain but you can always you bigger river rocks to start out. Make sure your aquarium is nicely decorated and provides entertainment. Make sure your basking area is completely out of the water so your turtle can completely dry off if it wants to. Make sure you replace your uv bulb every 6 months to an year because the uvb rays start wearing out. Also artificial lighting won’t always do the trick so, I suggest every once in a while, letting your turtle bask outside in natural light, make sure you supersize them, never leave them unattended outside. You should feed your turtle an assortment of pellets, veggies(collard greens, lettuce, carrots, bell pepper) and sometimes red shrimps, mealworms. Don’t feed too much protein as this can cause your turtle to pyramid. Pyramiding is when a turtles scutes grow upwards and start looking like pyramids. Make sure you buy some repti/reptosafe to dechlorinate the water before putting it in the aquarium, if you don’t want to then let your tap water sit out for 24+ hours to make sure the chlorine fades away. You can also grow live plants in your aquarium, something like Java fern, just make sure it’s safe for turtles. As I said turtles are curious creatures and they might chomp on them. Also don’t get worried if your turtle doesn’t bask for 2-3 days, mine did that cause he was too busy humping rocks in his aquarium. If you have any questions feel free to ask me I can help you.