1. Requirements
The most important part is selecting components based on requirements - we will verify that each component we select satisfies the requirements, so you can save yourself time by only considering components that satisfy our requirements
2. DigiKey search
https://www.digikey.com/products/en
First, select the category of the product you're looking for. Then, DigiKey lets you filter by all possible parameters. Filter until you get a few results and then look at the datasheets
3. Datasheet
As James pointed out, some parts have their TI equivalents, so you can try looking for a TI datasheet even if the part is manufacture by someone else. In general, TI has amazing datasheets.
Most datasheets will have a lot of useful information on the front page, like most important specs (e. g. acceleration range for an IMU), so definitely look through that. Later, don't read the whole datasheet just yet; look for application notes and basic power requirements/characteristics (@James need more ideas here).
Make sure that all of these meet the requirements.
4. Use your resources
Look for what other people are using in rocketry or in other applications, ask others if they've used cool things before.
5. Help each other
If you are looking for an IMU but found a cool barometer: put the link as a comment on the barometer task! The person looking for the barometer might have not seen the part before and it might be a good one.
This page will be improved further!