Welcome to Stangnet dwilson8, and the wonderful world of car tuning! What have you done to the engine so far? and what year/model is it?
probably one of the easiest ways to gain considerable HP, is a larger exhaust sytem, and a header. (maybe from a ranger) The more you spend on an exhaust system,(in general) the more HP you stand to gain. A more agressive camshaft can net you some more HP, but it may degrade your low RPM performance, depending on the cam. Many people like to grab a Ranger roller cam and followers from the local junkyard. Then you got a very nice, low friction, mildly agressive street cam.
If you are a little low on funds, like myself, try some DIY mods. You can do away with the air cleaner box, and add a K&N (or similar) air filter for a couple easy HP. some people like to gut the air silencer, although it wont get ya much power. the better, but harder way, would be to build your own CAI (Cold Air Intake) from PVC Pipe, for example. Or, of corse, you could try to find something prefab, but i understand they can be hard to find.
Later on, you can look into porting the intake. You could also gut the upper intake, and knife edge the lower. This essentially gives you a shorter intake runner, adding to high end power. porting the head and adding bigger valves can get you some better performance all around. some tighter valve springs can raise your redline by 1k or so.
May sound a little overwhelming, but pick a couple easy things, and set aside a weekend and see what you can do to give yer ride a little more pep.
-Ryan