I use to take creatine and wheat germ when I was doing alot of running and lifting. I didn't take it all the time because I couldn't afford it. What helped me the most was just eating a balanced diet and cutting out junk foods.

Good Luck!

Eggwhites are pretty safe unless you are allergic.
A high quality whey protein isolate has less side effects than many other powders. I use the one from saschafitness.com and have good luck with it. You want to look at the nutrition panel. Look at how many grams are in a serving, then how many grams of protein are in a serving. Should be about the same number within like 3 grams. If the protein is much less than the grams per serving, then that powder has fillers that can bloat you or spike your sugar.
Also, as Bob mentioned above, creatine monohydrate is a great cheap supplement that can help you get thru more sets and make more gains.
You may hear alot about BCAAs or amino acids too. Those are good to take before a workout, and many good protein powders you can drink after a workout or before bed will have BCAAs to help with soreness.
Honestly tho, if you can, start supplementing with eggwhites. Increasing meat consumption is probably where you heard ppl talk about kidney issues. Also eggwhites are sold alone near the eggs at most supermarkets much cheaper than meat. Chunk lite tuna in water is another cheap easy to digest source of protein. Maybe incorporate a can of that everyday to your diet if you aren't allergic and like it. Other great sources of protein is black beans and low-fat cottage cheese. Again, if you aren't allergic, those are good to start with and shouldn't give you tummy or other troubles.