Get an oven thermometer to make sure you're baking at the correct temp.

Read everything Stella Parks has to say about technique. Use a digital kitchen scale to weigh your ingredients!

Get your recipes from trustworthy sources. Serious Eats, King Arthur Flour, and America's Test Kitchen (paywall unfortunately), are my favorite sources for both recipes and technique! YouTube videos and random blogs are usually risky sources.

Beware of regional differences in ingredients. If you aren't in the US, you'll want to find other sources for trusted recipes because the ones I linked are all US based. If you are in the US, be careful using recipes from the UK, Europe, or asia. Some might work just fine, but others will be total flops because of regional differences.

If you want to try using cake strips without the cost investment, you can fold paper towels into strips, wet them, and stick them to the side of your cake pans for a cheap cake strip substitute.

Finally, slight domes on cakes aren't the end of the world! I'd much rather have a dome that I have to trim off than have a rough crumb or any other texture or flavor issue!

get an oven thermometer so you can somewhat verify your temperatures. cant trust the dials.