I will touch on each of them starting with the least powerful. However every one of these activities can contribute to what you want your firm to become.
This is an incomplete list of things that reflect on you and help/hurt your image: firm name, logo, stationery, business cards, physical location, website look and feel, domain-name email, project signs, automobile, clothes, etc. These things don't matter much if your image is a struggling, hungry start-up. However, to the extent that you want to "punch above your weight" and be considered for 'where you are going' rather than 'where you are', they matter a lot.
RFQs take two forms - the private and the public owners. To some extent providing RFQs might be a temporary necessity, but they lead to becoming a commodity. Nevertheless you want to put out information that a private client might find worth considering. The format is up to you. The public clients, like state, federal, and governmental agencies have their qualification processes that vet the firms who want to work for them. At the federal level this is the Standard Form 330. The idea for both types of clients is to put information in front of the people that you think will be selecting architects.
Promotion takes several forms such as direct mail, newsletters, ads, sponsorships, events, Facebook(?), and so on. Direct mail consists of sending a letter/post card/brochure/pamphlet or similar piece to a mailing list. Response rates are normally very low, so you are just trying to remind the recipient that you exist. Newsletters could take the direct mail approach or be the email version, which has the benefit of costing about 5% of the hardcopy version. The hitch is that it will take much, much longer to build an email list than a mailing list. Ads are obvious; most are expensive for their return, except the electronic variety using, say, Google AdWords, Facebook or LinkedIn. A sponsorship of someone else's event is like advertising; or you could hold your own event to celebrate a milestone or support a worthy (and related?) charity or civic project. Facebook is a good way to keep your name in front of your "Likes". This could be especially useful if your target audience is individuals rather than organizations.
Networking is basically making connections - in person through the Chamber of Commerce, social clubs, alum organizations, church, friends, family; or electronically through LinkedIn, perhaps even Facebook qualifies as networking as long as there is interaction. See Matt Handal's article on how to do it right.
Relationship-building is a takeoff on networking; but, at least in my mind, it is different because it is more targeted - you are seeking out people to contact with the sole purpose of finding a way to help them and become their go-to person for all their design and construction questions.
As I have mentioned before, building a niche, while time-consuming (and measured in years), is the ideal form of marketing your firm because eventually you have your clients seeking you out because of your specialty. There is not only less competition, there may be none. Your fees are whatever the market will bear and your productivity is sky high. I would recommend that you do all of these things with the idea of establishing your niche ... say, biophilia-inspired dwellings!