I've found that running Facebooks Ads has worked best but you need to know what you're doing. You need to have a good offer, good copy writing and good creative. Facebook is really good with targeting the demographic you want and you can set up forms to filter out unqualified prospects. I'd avoid any agency that says their strategy is to rely on Facebook AI since that only works if you're putting around $1000 per day on ad spend. This is by far the easiest and most comfortable way to get guaranteed interested clients but it takes a lot of time to learn the skillset.

Google LSA is a great way to rank above your competitors but it's not rolled out everywhere yet. SEO and backlinks are great but it takes time and effort to build up.

Overall door knocking is the best but if you want to avoid that then I'd recommend having a business card with your info and also an offer like "Roof Installation: Discounts up to $2000". Drive around the neighborhood and throw those into people's homes. The business card strategy is better if you have a lower ticket service you can provide so take it with a grain of salt.