You can just go boom: idea -> development -> publish, but how will people know your product exists and what it does? Advertising!
I recently released Atlas Fury, an arcade style space shooter for iPhone (App Store) and Android (Google Play) so I had a need to spread awareness through multiple channels. Hey, we hit 1k+ downloads on the Play Store after around 3-4 days.
Paid advertising is commonly thought about with influencer partnering, display networks, Youtube ads or App Store marketing. Then there's the targeted campaign where you reach out to communities on social media and other forums. Finally, they will come campaign where you put the product out there optimize keywords and hope. It's a lottery in the end if any or all succeed.
With paid advertising you need a large budget, patience and an idea of how advertising works on the backend to understand how the options you chose affect your spend. When you use Meta/Facebook/Instagram Ads or Google Ads they have a market to serve both advertisers and publishers.
You are an advertiser if you seek to display media somewhere and/or publisher if you display ads in your product. As an advertiser you want to know terms like CPC, CPA, CPM (lets combine this into CPX) because you are paying for all of those. When your ads are going to be put on the market there are auctions going on. Google and co. attempt to bid to get your ads placed and the one who wins is the one whose ads get served. This happens billions, if not trillions, of times per day.
If you have high CPX then you are going to blow your budget very quickly every day and you potentially inflate the market since you starve out the others. If you have low CPX, you will not be seen as often because you aren't winning bids + you don't get prime time spots. Think about it, how do you moderate your spend then to increase ROI? That's where targeting comes in. The more information you have on users, the more your bids can be targeted towards specific audiences. That's why Facebook and Co. want your data.
You add targeting to your ad because you want to reach specific people otherwise you might find yourself blowing your budget because too broad of an audience. You need to experiment and exclude until you feel that your ad dollars are spent well per hour.
If you have small budgets, use more exclusions. Target a specific subset of people. Target specific countries. Use multiple campaigns to limit spend to certain regions since one or so regions can blow through your budget. Larger budgets means broader global audience, but not necessarily better ROI, just most likely better growth.
Use slightly larger budgets than your intended to experiment with new targeting options and decrease or stop it as time goes on if you do not get the ROI you want. Keep experimenting. It's the only way to get better ROI.
As a publisher, there could be settings to adjust CPX so you get higher quality ads displayed on your app so you don't get trash though too high of a CPX will mean you win no auctions therefore little to no revenue. Also, make sure to set the maximum rating on the platform or software so rated (E)veryone apps don't get rated (A)dult ads. Geez.
When it comes to your ad assets, make sure they look good enough. No need for perfect since you can iterate here. Monitor the stats as you want to cull out bad performing ads based on the data collected quickly. Text, images, videos all need to be changed. Videos are harder to change since there is more time investment, so you need to have a video editor (software or person) on hand ready to change things or make new videos and it has to start early in since the ads will run while that development going on.
Yeah, many people are discouraged from paid advertising because there's a certain amount of waste (click fraud, badly targeted, terrible goals) associated and much learning to be had. Money money money is needed to experiment and optimize.
Advertising is hard, but if you can make the best of it you'll be a legend.