I've been meaning to re-start this conversation for some time. We had some real long and very good threads on the old boards with lotsa good reading and tips. I'm going to list a few and hopefully youse guys will add your favorites.
One of the first acquisitions any gun owner/manly type man should make is a decent set of screwdrivers. Even Wally world sell the multi-tip type kits these days and while the quality isn't up to what you'd get from Brownells (www.brownells.com) it'll do for 80% of what you need. Find the tip that fits the screw driver slot, file or grind it to fit if needed. The sloppy fitting bit is the one that will booger up the screws on that nice hunk o'metal you payed good dollars for.
On a tight screw- get a close fitting screw driver and whack it a couple times with your plastic mallet. It helps loosen the screw. What? You don't have a plastic mallet? How about a rawhide mallet? Come on, you must at least have a brass hammer for your gun work? Better get one of the above because they plain work better for gun work. Plus you need one to knock your sprue plate aside. If that screw still won't loosen apply a bit of heat. This can be from a soldering gun, (make sure the tip has a wet appearance or the heat transfer is very slow), a very tiny flame from one of those mini torches, ( about 12 bucks at Wally world, runs on Butane), or by heating a metal object like a bolt that is close in size to the screw head in a flame and holding it to the screwhead, with PLIERS dummy, after it's nice and hot. Penetrating oils and solvents help too. Just don't do like I do and try excessive force first.
Speaking of pliers- Get 4 or5 pair. Different types and shapes are handy. Farm type stores, TSC for example, have nifty assortments made in far off china of dubious quality that are perfect. When you paid .99 cents for the pliers you don't mind grinding them or bending them into the shape you need. I'm talking needle nose type pliers in addition to the regular slip-joint style. Then there are Vise-grips. Gotta have 2 or 3 of them. For gun work you need the smaller needle nose type mostly. They're what you hold that hot bolt to the stuck screw with. This is one area where brand name products pay for themselves. I have never found any other brand other than Vise-grip to be worth a snot.
A vise of some sort is real handy. I see there are some plastic woodworking vises these days that work good for anything not involving heat. I've got one and it's handy. It will never replace a real bench vise though. Even a small clamp on vise will serve you if it's solid enough.
Files. Ah, files. There are 348,000 gazillion types, shapes and grades out there. Get a 8" mill bastard, a 6" triangle, and a set of needle files. Stop there until you figure out what you need next. Keep your files stored so they don't touch each other, that dulls them. Don't drag your file backwards across the work, lift it up for the return, dragging dulls your file. It's not a saw. Put a handle on the file, any handle is better than none. Spray the file with WD-40 occasionally, keeps rust off and helps when you go to clean the file. Either get a file card, (a brush looking thing with steel teeth that you push across the file teeth to scrape out the bits of metal stuck there that leave tose lines in your work), or sharpen a nail to remove the metal stuck in the file teeth. Prolongs the files life and makes it cut better. If you develop the habit of cleaning the file right after your done with it small children and beautiful women will adore you, or so I'm told.
Storage- Peg borad is wonderfull becasue you can see all your tools, except that it's expensive and everyone can see all your tools and try and steal them. Plus those little hooks always fall out on me. I like tool cabinets, but to start with a sturdy cardboard box will do, providing theres a safe dry location for it. I also have one of those lazy-susan tool holders that real handy, only I don't see them for sale anymore. Yard sales maybe. Whatever you do, organization helps make for better work.
Big storage- 5 gallon buckets reign supreme, at least on my farm. At a dollar a piece or free they makes great storage for wheel weights, hammers, prybars, shovels, axes, rope, lead cords, sawdust, odd wood scraps, cats, rags, wax, traps, your mother in laws ashes, car parts, old oil, chainsaws (bar down), nuts and bolts till you get something better, kitty litter (oil soak), really big runs of boolits, for quenching said boolits, dis-membered bodies (minus torso, don't ask why I know this), old inner tubes for making scope covers and sling shots, salt for the driveway and walk (those who don't know why you need salt for the driveway- consider yourselves blessed), nifty rocks and fungus you find while hunting, your wheat penney collection- you get the idea. Plus, as an added benefit they work great for drowning yourself when you find out your unemployed brother in law, his drunk wife and their 7 brats are coming "for a visit".
Grinders- You need something to grind with. Either a bench grinder- a cheap 6" $30.00 grinder is fine, or at least one of those holders for a drill motor or a Dremel. A Dremel, or a cheap knock off copy, is almost a neccessity. Just wear safety glasses waht ever you get. I can show you some nifty x-rays if you really don't know why you need glasses. Remember that grinding creates heat which softens metal and burns the fingers holding the metal. Go slow and easy. You can't put the metal you ground off back, not with out a lot of work anyway. With a good hacksaw, a grinder and a file you can make an astounding number of gadgets, geegaws, and whatsits for your castng/gun/reloading hobby.