General principles of negotiation say it is better to appear strong than weak. However, it's bad to appear DANGEROUS. Some people are so terrified of Niefel Giants that they won't rest until Niefelheim is extinct. I suspect that e.g. Marverni can get away with pulling ahead on the research graph where LA R'lyeh could not. You might try combining an appearance of strength with NAPs with your weaker neighbors; assure them that you'll be going after somebody else if they'll consent to support you with some minor tribute. Paradoxically, paying tribute could make them feel safer (as long as it's cheap) because it gives you a reason to want them around. If you phrase it nicely enough they might even think you're spearheading an alliance.
-Maximilian
Edit: another way to make people feel threatened is to keep them in the dark. Conversely, it might be useful to provide strategic information to your tributaries when you extort money from them. "Player X has 300 Z units parked in provinces A, B, and C. I want to build 200 Ys to attack him. I need an extra 200 gold from you to make this work." If you've done things right they'll be eager to be helpful as long as you can protect them from retaliation by X. If you wanted to you could also lie about how many units are involved to make yourself look bigger and tougher to your tributaries. Of course I would never condone outright lying but maybe Yublub the Old Old One, Dweller in Everlasting Burnings has a different perspective on the matter.
