If you want to plant tomatoes and peppers together, it is highly recommended that you only plant one of each so there are minimal complications. While it can certainly be tricky to plant peppers and tomatoes together, it is definitely possible if you know what you are doing. Both peppers and tomatoes have very similar growing needs though, so you will find that it is easy to take care of them. Peppers and tomatoes also both need full sun in order to grow properly.
Make sure that the peppers and tomatoes you are planting are at least several feet apartment as you do not want them competing for the nutrients they need to grow. Also make sure to rotate your crops once in a while so you can prevent disease building up in the soil. It can become a serious problem over time which can spell the demise of your plants unless you do this regularly. Those who are interested in planting these two things together should also know that it is important to get disease-resistant tomatoes and peppers so you can reduce your chances of problems with disease.