A holy city it may be, but Rishikesh draws more than its fair share of criminals and conmen. Don't walk around alone at night and beware of the motives of sadhus offering one-on-one tutoring. There is also a gem stone hoax going on in at least one gem store: They ask you to bring the stones to your own country to a "buyer" who doesn't exist.
Watch where you step:After sundown it is pitch dark, so bring a light. Watch out for the sometimes brash food stealing monkeys too. They mostly "operate" on and around the foot bridges, and if you look them in the eyes they become aggressive, but rarely/never attack unless you carry food. Sadhus and police officers carry sticks to keep monkeys and cows/oxen at a distance. The brown monkeys are aggressive; the grey big languors are nicer. They greys sometimes steal food from tourists not on the bridges, but mostly because their size scares the tourist, they don't bite you over food matters.
Be alert if an ox is on your path: They are mostly harmless, but after dark they are sometimes nervous. Especially on the narrow foot bridges, you should try to read their body language before a close encounter.
Try not getting involved with any local guide, whose offering you services.They are mostly con men and goons.