[thenerdhead]

You can't really just give people advice unless they ask for it. You can however ask people if it's okay to give them advice or how you can do that best.

Sometimes it is even useful to ask said person who might benefit from advice for advice. That opens the conversation to being receptive of each other's advice.

Lastly, you should probably question yourself regarding why your advice should be accepted in the first place. Majority of the time people will figure it out and your inaction of giving said advice is actually more helpful in the long run.