What shall we do before exercsing?

Now it is in winter, we should exercise our body  to improve our immunity. But what shall we care about before exercsing?  Of course, before we go to exercise,

we should wear comfortable clothes and shoes and others. Let's see the below which we should care more about them:

1.Dont exercise if empty stomach or  after lunch or dinner. It is better to exercise one hour later  after eating goods.

2.We should warm up our body at least 5 minutes. It can protect our body hurt during exercsing.

3. It is better to employ a private trainer to help you to arrange reasonable exercise program. Private trainer will make exercsing plan depend on your body.

4.When the exercising will be finished, keep slow actions. Dont stop actions suddenly.